services/core/java/com/android/server/media/MediaSessionService.java

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.server.media;

import static android.os.UserHandle.USER_ALL;

import android.annotation.Nullable;
import android.app.ActivityManager;
import android.app.INotificationManager;
import android.app.KeyguardManager;
import android.app.PendingIntent;
import android.app.PendingIntent.CanceledException;
import android.content.ActivityNotFoundException;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.ParceledListSlice;
import android.content.pm.ServiceInfo;
import android.content.pm.UserInfo;
import android.database.ContentObserver;
import android.media.AudioManager;
import android.media.AudioManagerInternal;
import android.media.AudioPlaybackConfiguration;
import android.media.AudioSystem;
import android.media.IAudioService;
import android.media.IRemoteVolumeController;
import android.media.MediaController2;
import android.media.Session2CommandGroup;
import android.media.Session2Token;
import android.media.session.IActiveSessionsListener;
import android.media.session.ICallback;
import android.media.session.IOnMediaKeyListener;
import android.media.session.IOnVolumeKeyLongPressListener;
import android.media.session.ISession;
import android.media.session.ISession2TokensListener;
import android.media.session.ISessionCallback;
import android.media.session.ISessionManager;
import android.media.session.MediaSession;
import android.media.session.MediaSessionManager;
import android.net.Uri;
import android.os.Binder;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerExecutor;
import android.os.IBinder;
import android.os.Message;
import android.os.PowerManager;
import android.os.Process;
import android.os.RemoteCallbackList;
import android.os.RemoteException;
import android.os.ResultReceiver;
import android.os.ServiceManager;
import android.os.UserHandle;
import android.os.UserManager;
import android.provider.Settings;
import android.speech.RecognizerIntent;
import android.text.TextUtils;
import android.util.Log;
import android.util.Slog;
import android.util.SparseArray;
import android.util.SparseIntArray;
import android.view.KeyEvent;
import android.view.ViewConfiguration;

import com.android.internal.annotations.GuardedBy;
import com.android.internal.util.DumpUtils;
import com.android.server.LocalServices;
import com.android.server.SystemService;
import com.android.server.Watchdog;
import com.android.server.Watchdog.Monitor;

import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

/**
 * System implementation of MediaSessionManager
 */
public class MediaSessionService extends SystemService implements Monitor {
    private static final String TAG = "MediaSessionService";
    static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
    // Leave log for key event always.
    private static final boolean DEBUG_KEY_EVENT = true;

    private static final int WAKELOCK_TIMEOUT = 5000;
    private static final int MEDIA_KEY_LISTENER_TIMEOUT = 1000;

    private final Context mContext;
    private final SessionManagerImpl mSessionManagerImpl;
    private final MessageHandler mHandler = new MessageHandler();
    private final PowerManager.WakeLock mMediaEventWakeLock;
    private final int mLongPressTimeout;
    private final INotificationManager mNotificationManager;
    private final Object mLock = new Object();
    // Keeps the full user id for each user.
    @GuardedBy("mLock")
    private final SparseIntArray mFullUserIds = new SparseIntArray();
    @GuardedBy("mLock")
    private final SparseArray<FullUserRecord> mUserRecords = new SparseArray<FullUserRecord>();
    @GuardedBy("mLock")
    private final ArrayList<SessionsListenerRecord> mSessionsListeners =
            new ArrayList<SessionsListenerRecord>();
    // Map user id as index to list of Session2Tokens
    // TODO: Keep session2 info in MediaSessionStack for prioritizing both session1 and session2 in
    //       one place.
    @GuardedBy("mLock")
    private final SparseArray<List<Session2Token>> mSession2TokensPerUser = new SparseArray<>();
    @GuardedBy("mLock")
    private final List<Session2TokensListenerRecord> mSession2TokensListenerRecords =
            new ArrayList<>();

    private KeyguardManager mKeyguardManager;
    private IAudioService mAudioService;
    private AudioManagerInternal mAudioManagerInternal;
    private ActivityManager mActivityManager;
    private ContentResolver mContentResolver;
    private SettingsObserver mSettingsObserver;
    private boolean mHasFeatureLeanback;

    // The FullUserRecord of the current users. (i.e. The foreground user that isn't a profile)
    // It's always not null after the MediaSessionService is started.
    private FullUserRecord mCurrentFullUserRecord;
    private MediaSessionRecord mGlobalPrioritySession;
    private AudioPlayerStateMonitor mAudioPlayerStateMonitor;

    // Used to notify System UI and Settings when remote volume was changed.
    @GuardedBy("mLock")
    final RemoteCallbackList<IRemoteVolumeController> mRemoteVolumeControllers =
            new RemoteCallbackList<>();

    public MediaSessionService(Context context) {
        super(context);
        mContext = context;
        mSessionManagerImpl = new SessionManagerImpl();
        PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
        mMediaEventWakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "handleMediaEvent");
        mLongPressTimeout = ViewConfiguration.getLongPressTimeout();
        mNotificationManager = INotificationManager.Stub.asInterface(
                ServiceManager.getService(Context.NOTIFICATION_SERVICE));
    }

    @Override
    public void onStart() {
        publishBinderService(Context.MEDIA_SESSION_SERVICE, mSessionManagerImpl);
        Watchdog.getInstance().addMonitor(this);
        mKeyguardManager = (KeyguardManager) mContext.getSystemService(Context.KEYGUARD_SERVICE);
        mAudioService = getAudioService();
        mAudioManagerInternal = LocalServices.getService(AudioManagerInternal.class);
        mActivityManager =
                (ActivityManager) mContext.getSystemService(Context.ACTIVITY_SERVICE);
        mAudioPlayerStateMonitor = AudioPlayerStateMonitor.getInstance(mContext);
        mAudioPlayerStateMonitor.registerListener(
                (config, isRemoved) -> {
                    if (config.getPlayerType()
                            == AudioPlaybackConfiguration.PLAYER_TYPE_JAM_SOUNDPOOL) {
                        return;
                    }
                    synchronized (mLock) {
                        FullUserRecord user = getFullUserRecordLocked(
                                UserHandle.getUserId(config.getClientUid()));
                        if (user != null) {
                            user.mPriorityStack.updateMediaButtonSessionIfNeeded();
                        }
                    }
                }, null /* handler */);
        mContentResolver = mContext.getContentResolver();
        mSettingsObserver = new SettingsObserver();
        mSettingsObserver.observe();
        mHasFeatureLeanback = mContext.getPackageManager().hasSystemFeature(
                PackageManager.FEATURE_LEANBACK);
        updateUser();
    }

    private IAudioService getAudioService() {
        IBinder b = ServiceManager.getService(Context.AUDIO_SERVICE);
        return IAudioService.Stub.asInterface(b);
    }

    private boolean isGlobalPriorityActiveLocked() {
        return mGlobalPrioritySession != null && mGlobalPrioritySession.isActive();
    }

    void updateSession(MediaSessionRecord record) {
        synchronized (mLock) {
            FullUserRecord user = getFullUserRecordLocked(record.getUserId());
            if (user == null) {
                Log.w(TAG, "Unknown session updated. Ignoring.");
                return;
            }
            if ((record.getFlags() & MediaSession.FLAG_EXCLUSIVE_GLOBAL_PRIORITY) != 0) {
                if (DEBUG_KEY_EVENT) {
                    Log.d(TAG, "Global priority session is updated, active=" + record.isActive());
                }
                user.pushAddressedPlayerChangedLocked();
            } else {
                if (!user.mPriorityStack.contains(record)) {
                    Log.w(TAG, "Unknown session updated. Ignoring.");
                    return;
                }
                user.mPriorityStack.onSessionStateChange(record);
            }
            mHandler.postSessionsChanged(record.getUserId());
        }
    }

    void setGlobalPrioritySession(MediaSessionRecord record) {
        synchronized (mLock) {
            FullUserRecord user = getFullUserRecordLocked(record.getUserId());
            if (mGlobalPrioritySession != record) {
                Log.d(TAG, "Global priority session is changed from " + mGlobalPrioritySession
                        + " to " + record);
                mGlobalPrioritySession = record;
                if (user != null && user.mPriorityStack.contains(record)) {
                    // Handle the global priority session separately.
                    // Otherwise, it can be the media button session regardless of the active state
                    // because it or other system components might have been the lastly played media
                    // app.
                    user.mPriorityStack.removeSession(record);
                }
            }
        }
    }

    private List<MediaSessionRecord> getActiveSessionsLocked(int userId) {
        List<MediaSessionRecord> records = new ArrayList<>();
        if (userId == USER_ALL) {
            int size = mUserRecords.size();
            for (int i = 0; i < size; i++) {
                records.addAll(mUserRecords.valueAt(i).mPriorityStack.getActiveSessions(userId));
            }
        } else {
            FullUserRecord user = getFullUserRecordLocked(userId);
            if (user == null) {
                Log.w(TAG, "getSessions failed. Unknown user " + userId);
                return records;
            }
            records.addAll(user.mPriorityStack.getActiveSessions(userId));
        }

        // Return global priority session at the first whenever it's asked.
        if (isGlobalPriorityActiveLocked()
                && (userId == USER_ALL || userId == mGlobalPrioritySession.getUserId())) {
            records.add(0, mGlobalPrioritySession);
        }
        return records;
    }

    List<Session2Token> getSession2TokensLocked(int userId) {
        List<Session2Token> list = new ArrayList<>();
        if (userId == USER_ALL) {
            for (int i = 0; i < mSession2TokensPerUser.size(); i++) {
                list.addAll(mSession2TokensPerUser.valueAt(i));
            }
        } else {
            list.addAll(mSession2TokensPerUser.get(userId));
        }
        return list;
    }

    /**
     * Tells the System UI and Settings app that volume has changed on an active remote session.
     */
    public void notifyRemoteVolumeChanged(int flags, MediaSessionRecord session) {
        if (!session.isActive()) {
            return;
        }
        synchronized (mLock) {
            int size = mRemoteVolumeControllers.beginBroadcast();
            MediaSession.Token token = session.getSessionToken();
            for (int i = size - 1; i >= 0; i--) {
                try {
                    IRemoteVolumeController cb = mRemoteVolumeControllers.getBroadcastItem(i);
                    cb.remoteVolumeChanged(token, flags);
                } catch (Exception e) {
                    Log.w(TAG, "Error sending volume change.", e);
                }
            }
            mRemoteVolumeControllers.finishBroadcast();
        }
    }

    void onSessionPlaystateChanged(MediaSessionRecord record, int oldState, int newState) {
        synchronized (mLock) {
            FullUserRecord user = getFullUserRecordLocked(record.getUserId());
            if (user == null || !user.mPriorityStack.contains(record)) {
                Log.d(TAG, "Unknown session changed playback state. Ignoring.");
                return;
            }
            user.mPriorityStack.onPlaystateChanged(record, oldState, newState);
        }
    }

    void onSessionPlaybackTypeChanged(MediaSessionRecord record) {
        synchronized (mLock) {
            FullUserRecord user = getFullUserRecordLocked(record.getUserId());
            if (user == null || !user.mPriorityStack.contains(record)) {
                Log.d(TAG, "Unknown session changed playback type. Ignoring.");
                return;
            }
            pushRemoteVolumeUpdateLocked(record.getUserId());
        }
    }

    @Override
    public void onStartUser(int userId) {
        if (DEBUG) Log.d(TAG, "onStartUser: " + userId);
        updateUser();
    }

    @Override
    public void onSwitchUser(int userId) {
        if (DEBUG) Log.d(TAG, "onSwitchUser: " + userId);
        updateUser();
    }

    // Called when the user with the userId is removed.
    @Override
    public void onStopUser(int userId) {
        if (DEBUG) Log.d(TAG, "onStopUser: " + userId);
        synchronized (mLock) {
            // TODO: Also handle removing user in updateUser() because adding/switching user is
            //       handled in updateUser().
            FullUserRecord user = getFullUserRecordLocked(userId);
            if (user != null) {
                if (user.mFullUserId == userId) {
                    user.destroySessionsForUserLocked(USER_ALL);
                    mUserRecords.remove(userId);
                } else {
                    user.destroySessionsForUserLocked(userId);
                }
            }
            mSession2TokensPerUser.remove(userId);
            updateUser();
        }
    }

    @Override
    public void monitor() {
        synchronized (mLock) {
            // Check for deadlock
        }
    }

    protected void enforcePhoneStatePermission(int pid, int uid) {
        if (mContext.checkPermission(android.Manifest.permission.MODIFY_PHONE_STATE, pid, uid)
                != PackageManager.PERMISSION_GRANTED) {
            throw new SecurityException("Must hold the MODIFY_PHONE_STATE permission.");
        }
    }

    void sessionDied(MediaSessionRecord session) {
        synchronized (mLock) {
            destroySessionLocked(session);
        }
    }

    void destroySession(MediaSessionRecord session) {
        synchronized (mLock) {
            destroySessionLocked(session);
        }
    }

    private void updateUser() {
        synchronized (mLock) {
            UserManager manager = (UserManager) mContext.getSystemService(Context.USER_SERVICE);
            mFullUserIds.clear();
            List<UserInfo> allUsers = manager.getUsers();
            if (allUsers != null) {
                for (UserInfo userInfo : allUsers) {
                    if (userInfo.isManagedProfile()) {
                        mFullUserIds.put(userInfo.id, userInfo.profileGroupId);
                    } else {
                        mFullUserIds.put(userInfo.id, userInfo.id);
                        if (mUserRecords.get(userInfo.id) == null) {
                            mUserRecords.put(userInfo.id, new FullUserRecord(userInfo.id));
                        }
                    }
                    if (mSession2TokensPerUser.get(userInfo.id) == null) {
                        mSession2TokensPerUser.put(userInfo.id, new ArrayList<>());
                    }
                }
            }
            // Ensure that the current full user exists.
            int currentFullUserId = ActivityManager.getCurrentUser();
            mCurrentFullUserRecord = mUserRecords.get(currentFullUserId);
            if (mCurrentFullUserRecord == null) {
                Log.w(TAG, "Cannot find FullUserInfo for the current user " + currentFullUserId);
                mCurrentFullUserRecord = new FullUserRecord(currentFullUserId);
                mUserRecords.put(currentFullUserId, mCurrentFullUserRecord);
                if (mSession2TokensPerUser.get(currentFullUserId) == null) {
                    mSession2TokensPerUser.put(currentFullUserId, new ArrayList<>());
                }
            }
            mFullUserIds.put(currentFullUserId, currentFullUserId);
        }
    }

    private void updateActiveSessionListeners() {
        synchronized (mLock) {
            for (int i = mSessionsListeners.size() - 1; i >= 0; i--) {
                SessionsListenerRecord listener = mSessionsListeners.get(i);
                try {
                    enforceMediaPermissions(listener.componentName, listener.pid, listener.uid,
                            listener.userId);
                } catch (SecurityException e) {
                    Log.i(TAG, "ActiveSessionsListener " + listener.componentName
                            + " is no longer authorized. Disconnecting.");
                    mSessionsListeners.remove(i);
                    try {
                        listener.listener
                                .onActiveSessionsChanged(new ArrayList<MediaSession.Token>());
                    } catch (Exception e1) {
                        // ignore
                    }
                }
            }
        }
    }

    /*
     * When a session is removed several things need to happen.
     * 1. We need to remove it from the relevant user.
     * 2. We need to remove it from the priority stack.
     * 3. We need to remove it from all sessions.
     * 4. If this is the system priority session we need to clear it.
     * 5. We need to unlink to death from the cb binder
     * 6. We need to tell the session to do any final cleanup (onDestroy)
     */
    private void destroySessionLocked(MediaSessionRecord session) {
        if (DEBUG) {
            Log.d(TAG, "Destroying " + session);
        }
        FullUserRecord user = getFullUserRecordLocked(session.getUserId());
        if (mGlobalPrioritySession == session) {
            mGlobalPrioritySession = null;
            if (session.isActive() && user != null) {
                user.pushAddressedPlayerChangedLocked();
            }
        } else {
            if (user != null) {
                user.mPriorityStack.removeSession(session);
            }
        }

        try {
            session.getCallback().asBinder().unlinkToDeath(session, 0);
        } catch (Exception e) {
            // ignore exceptions while destroying a session.
        }
        session.onDestroy();
        mHandler.postSessionsChanged(session.getUserId());
    }

    private void enforcePackageName(String packageName, int uid) {
        if (TextUtils.isEmpty(packageName)) {
            throw new IllegalArgumentException("packageName may not be empty");
        }
        String[] packages = mContext.getPackageManager().getPackagesForUid(uid);
        final int packageCount = packages.length;
        for (int i = 0; i < packageCount; i++) {
            if (packageName.equals(packages[i])) {
                return;
            }
        }
        throw new IllegalArgumentException("packageName is not owned by the calling process");
    }

    /**
     * Checks a caller's authorization to register an IRemoteControlDisplay.
     * Authorization is granted if one of the following is true:
     * <ul>
     * <li>the caller has android.Manifest.permission.MEDIA_CONTENT_CONTROL
     * permission</li>
     * <li>the caller's listener is one of the enabled notification listeners
     * for the caller's user</li>
     * </ul>
     */
    private void enforceMediaPermissions(ComponentName compName, int pid, int uid,
            int resolvedUserId) {
        if (hasStatusBarServicePermission(pid, uid)) return;
        if (mContext
                .checkPermission(android.Manifest.permission.MEDIA_CONTENT_CONTROL, pid, uid)
                != PackageManager.PERMISSION_GRANTED
                && !isEnabledNotificationListener(compName, UserHandle.getUserId(uid),
                resolvedUserId)) {
            throw new SecurityException("Missing permission to control media.");
        }
    }

    private boolean hasStatusBarServicePermission(int pid, int uid) {
        return mContext.checkPermission(android.Manifest.permission.STATUS_BAR_SERVICE,
                pid, uid) == PackageManager.PERMISSION_GRANTED;
    }

    private void enforceStatusBarServicePermission(String action, int pid, int uid) {
        if (!hasStatusBarServicePermission(pid, uid)) {
            throw new SecurityException("Only System UI and Settings may " + action);
        }
    }

    /**
     * This checks if the component is an enabled notification listener for the
     * specified user. Enabled components may only operate on behalf of the user
     * they're running as.
     *
     * @param compName The component that is enabled.
     * @param userId The user id of the caller.
     * @param forUserId The user id they're making the request on behalf of.
     * @return True if the component is enabled, false otherwise
     */
    private boolean isEnabledNotificationListener(ComponentName compName, int userId,
            int forUserId) {
        if (userId != forUserId) {
            // You may not access another user's content as an enabled listener.
            return false;
        }
        if (DEBUG) {
            Log.d(TAG, "Checking if enabled notification listener " + compName);
        }
        if (compName != null) {
            try {
                return mNotificationManager.isNotificationListenerAccessGrantedForUser(
                        compName, userId);
            } catch (RemoteException e) {
                Log.w(TAG, "Dead NotificationManager in isEnabledNotificationListener", e);
            }
        }
        return false;
    }

    private MediaSessionRecord createSessionInternal(int callerPid, int callerUid, int userId,
            String callerPackageName, ISessionCallback cb, String tag, Bundle sessionInfo)
            throws RemoteException {
        synchronized (mLock) {
            return createSessionLocked(callerPid, callerUid, userId, callerPackageName, cb,
                    tag, sessionInfo);
        }
    }

    /*
     * When a session is created the following things need to happen.
     * 1. Its callback binder needs a link to death
     * 2. It needs to be added to all sessions.
     * 3. It needs to be added to the priority stack.
     * 4. It needs to be added to the relevant user record.
     */
    private MediaSessionRecord createSessionLocked(int callerPid, int callerUid, int userId,
            String callerPackageName, ISessionCallback cb, String tag, Bundle sessionInfo) {
        FullUserRecord user = getFullUserRecordLocked(userId);
        if (user == null) {
            Log.w(TAG, "Request from invalid user: " +  userId + ", pkg=" + callerPackageName);
            throw new RuntimeException("Session request from invalid user.");
        }

        final MediaSessionRecord session = new MediaSessionRecord(callerPid, callerUid, userId,
                callerPackageName, cb, tag, sessionInfo, this, mHandler.getLooper());
        try {
            cb.asBinder().linkToDeath(session, 0);
        } catch (RemoteException e) {
            throw new RuntimeException("Media Session owner died prematurely.", e);
        }

        user.mPriorityStack.addSession(session);
        mHandler.postSessionsChanged(userId);

        if (DEBUG) {
            Log.d(TAG, "Created session for " + callerPackageName + " with tag " + tag);
        }
        return session;
    }

    private int findIndexOfSessionsListenerLocked(IActiveSessionsListener listener) {
        for (int i = mSessionsListeners.size() - 1; i >= 0; i--) {
            if (mSessionsListeners.get(i).listener.asBinder() == listener.asBinder()) {
                return i;
            }
        }
        return -1;
    }

    private int findIndexOfSession2TokensListenerLocked(ISession2TokensListener listener) {
        for (int i = mSession2TokensListenerRecords.size() - 1; i >= 0; i--) {
            if (mSession2TokensListenerRecords.get(i).listener.asBinder() == listener.asBinder()) {
                return i;
            }
        }
        return -1;
    }

    private void pushSessionsChanged(int userId) {
        synchronized (mLock) {
            FullUserRecord user = getFullUserRecordLocked(userId);
            if (user == null) {
                Log.w(TAG, "pushSessionsChanged failed. No user with id=" + userId);
                return;
            }
            List<MediaSessionRecord> records = getActiveSessionsLocked(userId);
            int size = records.size();
            ArrayList<MediaSession.Token> tokens = new ArrayList<MediaSession.Token>();
            for (int i = 0; i < size; i++) {
                tokens.add(records.get(i).getSessionToken());
            }
            pushRemoteVolumeUpdateLocked(userId);
            for (int i = mSessionsListeners.size() - 1; i >= 0; i--) {
                SessionsListenerRecord record = mSessionsListeners.get(i);
                if (record.userId == USER_ALL || record.userId == userId) {
                    try {
                        record.listener.onActiveSessionsChanged(tokens);
                    } catch (RemoteException e) {
                        Log.w(TAG, "Dead ActiveSessionsListener in pushSessionsChanged, removing",
                                e);
                        mSessionsListeners.remove(i);
                    }
                }
            }
        }
    }

    private void pushRemoteVolumeUpdateLocked(int userId) {
        FullUserRecord user = getFullUserRecordLocked(userId);
        if (user == null) {
            Log.w(TAG, "pushRemoteVolumeUpdateLocked failed. No user with id=" + userId);
            return;
        }

        synchronized (mLock) {
            int size = mRemoteVolumeControllers.beginBroadcast();
            MediaSessionRecord record = user.mPriorityStack.getDefaultRemoteSession(userId);
            MediaSession.Token token = record == null ? null : record.getSessionToken();

            for (int i = size - 1; i >= 0; i--) {
                try {
                    IRemoteVolumeController cb = mRemoteVolumeControllers.getBroadcastItem(i);
                    cb.updateRemoteController(token);
                } catch (Exception e) {
                    Log.w(TAG, "Error sending default remote volume.", e);
                }
            }
            mRemoteVolumeControllers.finishBroadcast();
        }
    }

    void pushSession2TokensChangedLocked(int userId) {
        List<Session2Token> allSession2Tokens = getSession2TokensLocked(USER_ALL);
        List<Session2Token> session2Tokens = getSession2TokensLocked(userId);

        for (int i = mSession2TokensListenerRecords.size() - 1; i >= 0; i--) {
            Session2TokensListenerRecord listenerRecord = mSession2TokensListenerRecords.get(i);
            try {
                if (listenerRecord.userId == USER_ALL) {
                    listenerRecord.listener.onSession2TokensChanged(allSession2Tokens);
                } else if (listenerRecord.userId == userId) {
                    listenerRecord.listener.onSession2TokensChanged(session2Tokens);
                }
            } catch (RemoteException e) {
                Log.w(TAG, "Failed to notify Session2Token change. Removing listener.", e);
                mSession2TokensListenerRecords.remove(i);
            }
        }
    }

    /**
     * Called when the media button receiver for the {@code record} is changed.
     *
     * @param record the media session whose media button receiver is updated.
     */
    public void onMediaButtonReceiverChanged(MediaSessionRecord record) {
        synchronized (mLock) {
            FullUserRecord user = getFullUserRecordLocked(record.getUserId());
            MediaSessionRecord mediaButtonSession =
                    user.mPriorityStack.getMediaButtonSession();
            if (record == mediaButtonSession) {
                user.rememberMediaButtonReceiverLocked(mediaButtonSession);
            }
        }
    }

    private String getCallingPackageName(int uid) {
        String[] packages = mContext.getPackageManager().getPackagesForUid(uid);
        if (packages != null && packages.length > 0) {
            return packages[0];
        }
        return "";
    }

    private void dispatchVolumeKeyLongPressLocked(KeyEvent keyEvent) {
        if (mCurrentFullUserRecord.mOnVolumeKeyLongPressListener == null) {
            return;
        }
        try {
            mCurrentFullUserRecord.mOnVolumeKeyLongPressListener.onVolumeKeyLongPress(keyEvent);
        } catch (RemoteException e) {
            Log.w(TAG, "Failed to send " + keyEvent + " to volume key long-press listener");
        }
    }

    private FullUserRecord getFullUserRecordLocked(int userId) {
        int fullUserId = mFullUserIds.get(userId, -1);
        if (fullUserId < 0) {
            return null;
        }
        return mUserRecords.get(fullUserId);
    }

    private MediaSessionRecord getMediaSessionRecordLocked(MediaSession.Token sessionToken) {
        FullUserRecord user = getFullUserRecordLocked(UserHandle.getUserId(sessionToken.getUid()));
        if (user != null) {
            return user.mPriorityStack.getMediaSessionRecord(sessionToken);
        }
        return null;
    }

    /**
     * Information about a full user and its corresponding managed profiles.
     *
     * <p>Since the full user runs together with its managed profiles, a user wouldn't differentiate
     * them when he/she presses a media/volume button. So keeping media sessions for them in one
     * place makes more sense and increases the readability.</p>
     * <p>The contents of this object is guarded by {@link #mLock}.
     */
    final class FullUserRecord implements MediaSessionStack.OnMediaButtonSessionChangedListener {
        public static final int COMPONENT_TYPE_INVALID = 0;
        public static final int COMPONENT_TYPE_BROADCAST = 1;
        public static final int COMPONENT_TYPE_ACTIVITY = 2;
        public static final int COMPONENT_TYPE_SERVICE = 3;
        private static final String COMPONENT_NAME_USER_ID_DELIM = ",";

        private final int mFullUserId;
        private final MediaSessionStack mPriorityStack;
        private PendingIntent mLastMediaButtonReceiver;
        private ComponentName mRestoredMediaButtonReceiver;
        private int mRestoredMediaButtonReceiverComponentType;
        private int mRestoredMediaButtonReceiverUserId;

        private IOnVolumeKeyLongPressListener mOnVolumeKeyLongPressListener;
        private int mOnVolumeKeyLongPressListenerUid;
        private KeyEvent mInitialDownVolumeKeyEvent;
        private int mInitialDownVolumeStream;
        private boolean mInitialDownMusicOnly;

        private IOnMediaKeyListener mOnMediaKeyListener;
        private int mOnMediaKeyListenerUid;
        private ICallback mCallback;

        FullUserRecord(int fullUserId) {
            mFullUserId = fullUserId;
            mPriorityStack = new MediaSessionStack(mAudioPlayerStateMonitor, this);
            // Restore the remembered media button receiver before the boot.
            String mediaButtonReceiverInfo = Settings.Secure.getStringForUser(mContentResolver,
                    Settings.System.MEDIA_BUTTON_RECEIVER, mFullUserId);
            if (mediaButtonReceiverInfo == null) {
                return;
            }
            String[] tokens = mediaButtonReceiverInfo.split(COMPONENT_NAME_USER_ID_DELIM);
            if (tokens == null || (tokens.length != 2 && tokens.length != 3)) {
                return;
            }
            mRestoredMediaButtonReceiver = ComponentName.unflattenFromString(tokens[0]);
            mRestoredMediaButtonReceiverUserId = Integer.parseInt(tokens[1]);
            if (tokens.length == 3) {
                mRestoredMediaButtonReceiverComponentType = Integer.parseInt(tokens[2]);
            } else {
                mRestoredMediaButtonReceiverComponentType =
                        getComponentType(mRestoredMediaButtonReceiver);
            }
        }

        public void destroySessionsForUserLocked(int userId) {
            List<MediaSessionRecord> sessions = mPriorityStack.getPriorityList(false, userId);
            for (MediaSessionRecord session : sessions) {
                destroySessionLocked(session);
            }
        }

        public void dumpLocked(PrintWriter pw, String prefix) {
            pw.print(prefix + "Record for full_user=" + mFullUserId);
            // Dump managed profile user ids associated with this user.
            int size = mFullUserIds.size();
            for (int i = 0; i < size; i++) {
                if (mFullUserIds.keyAt(i) != mFullUserIds.valueAt(i)
                        && mFullUserIds.valueAt(i) == mFullUserId) {
                    pw.print(", profile_user=" + mFullUserIds.keyAt(i));
                }
            }
            pw.println();
            String indent = prefix + "  ";
            pw.println(indent + "Volume key long-press listener: " + mOnVolumeKeyLongPressListener);
            pw.println(indent + "Volume key long-press listener package: "
                    + getCallingPackageName(mOnVolumeKeyLongPressListenerUid));
            pw.println(indent + "Media key listener: " + mOnMediaKeyListener);
            pw.println(indent + "Media key listener package: "
                    + getCallingPackageName(mOnMediaKeyListenerUid));
            pw.println(indent + "Callback: " + mCallback);
            pw.println(indent + "Last MediaButtonReceiver: " + mLastMediaButtonReceiver);
            pw.println(indent + "Restored MediaButtonReceiver: " + mRestoredMediaButtonReceiver);
            pw.println(indent + "Restored MediaButtonReceiverComponentType: "
                    + mRestoredMediaButtonReceiverComponentType);
            mPriorityStack.dump(pw, indent);
            pw.println(indent + "Session2Tokens:");
            for (int i = 0; i < mSession2TokensPerUser.size(); i++) {
                List<Session2Token> list = mSession2TokensPerUser.valueAt(i);
                if (list == null || list.size() == 0) {
                    continue;
                }
                for (Session2Token token : list) {
                    pw.println(indent + "  " + token);
                }
            }
        }

        @Override
        public void onMediaButtonSessionChanged(MediaSessionRecord oldMediaButtonSession,
                MediaSessionRecord newMediaButtonSession) {
            if (DEBUG_KEY_EVENT) {
                Log.d(TAG, "Media button session is changed to " + newMediaButtonSession);
            }
            synchronized (mLock) {
                if (oldMediaButtonSession != null) {
                    mHandler.postSessionsChanged(oldMediaButtonSession.getUserId());
                }
                if (newMediaButtonSession != null) {
                    rememberMediaButtonReceiverLocked(newMediaButtonSession);
                    mHandler.postSessionsChanged(newMediaButtonSession.getUserId());
                }
                pushAddressedPlayerChangedLocked();
            }
        }

        // Remember media button receiver and keep it in the persistent storage.
        public void rememberMediaButtonReceiverLocked(MediaSessionRecord record) {
            PendingIntent receiver = record.getMediaButtonReceiver();
            mLastMediaButtonReceiver = receiver;
            mRestoredMediaButtonReceiver = null;
            mRestoredMediaButtonReceiverComponentType = COMPONENT_TYPE_INVALID;

            String mediaButtonReceiverInfo = "";
            if (receiver != null) {
                ComponentName component = receiver.getIntent().getComponent();
                if (component != null
                        && record.getPackageName().equals(component.getPackageName())) {
                    String componentName = component.flattenToString();
                    int componentType = getComponentType(component);
                    mediaButtonReceiverInfo = String.join(COMPONENT_NAME_USER_ID_DELIM,
                            componentName, String.valueOf(record.getUserId()),
                            String.valueOf(componentType));
                }
            }
            Settings.Secure.putStringForUser(mContentResolver,
                    Settings.System.MEDIA_BUTTON_RECEIVER, mediaButtonReceiverInfo,
                    mFullUserId);
        }

        private void pushAddressedPlayerChangedLocked() {
            if (mCallback == null) {
                return;
            }
            try {
                MediaSessionRecord mediaButtonSession = getMediaButtonSessionLocked();
                if (mediaButtonSession != null) {
                    mCallback.onAddressedPlayerChangedToMediaSession(
                            mediaButtonSession.getSessionToken());
                } else if (mCurrentFullUserRecord.mLastMediaButtonReceiver != null) {
                    mCallback.onAddressedPlayerChangedToMediaButtonReceiver(
                            mCurrentFullUserRecord.mLastMediaButtonReceiver
                                    .getIntent().getComponent());
                } else if (mCurrentFullUserRecord.mRestoredMediaButtonReceiver != null) {
                    mCallback.onAddressedPlayerChangedToMediaButtonReceiver(
                            mCurrentFullUserRecord.mRestoredMediaButtonReceiver);
                }
            } catch (RemoteException e) {
                Log.w(TAG, "Failed to pushAddressedPlayerChangedLocked", e);
            }
        }

        private MediaSessionRecord getMediaButtonSessionLocked() {
            return isGlobalPriorityActiveLocked()
                    ? mGlobalPrioritySession : mPriorityStack.getMediaButtonSession();
        }

        private int getComponentType(@Nullable ComponentName componentName) {
            if (componentName == null) {
                return COMPONENT_TYPE_INVALID;
            }
            PackageManager pm = mContext.getPackageManager();
            try {
                ActivityInfo activityInfo = pm.getActivityInfo(componentName,
                        PackageManager.MATCH_DIRECT_BOOT_AWARE
                                | PackageManager.MATCH_DIRECT_BOOT_UNAWARE
                                | PackageManager.GET_ACTIVITIES);
                if (activityInfo != null) {
                    return COMPONENT_TYPE_ACTIVITY;
                }
            } catch (NameNotFoundException e) {
            }
            try {
                ServiceInfo serviceInfo = pm.getServiceInfo(componentName,
                        PackageManager.MATCH_DIRECT_BOOT_AWARE
                                | PackageManager.MATCH_DIRECT_BOOT_UNAWARE
                                | PackageManager.GET_SERVICES);
                if (serviceInfo != null) {
                    return COMPONENT_TYPE_SERVICE;
                }
            } catch (NameNotFoundException e) {
            }
            // Pick legacy behavior for BroadcastReceiver or unknown.
            return COMPONENT_TYPE_BROADCAST;
        }
    }

    final class SessionsListenerRecord implements IBinder.DeathRecipient {
        public final IActiveSessionsListener listener;
        public final ComponentName componentName;
        public final int userId;
        public final int pid;
        public final int uid;

        SessionsListenerRecord(IActiveSessionsListener listener,
                ComponentName componentName,
                int userId, int pid, int uid) {
            this.listener = listener;
            this.componentName = componentName;
            this.userId = userId;
            this.pid = pid;
            this.uid = uid;
        }

        @Override
        public void binderDied() {
            synchronized (mLock) {
                mSessionsListeners.remove(this);
            }
        }
    }

    final class Session2TokensListenerRecord implements IBinder.DeathRecipient {
        public final ISession2TokensListener listener;
        public final int userId;

        Session2TokensListenerRecord(ISession2TokensListener listener,
                int userId) {
            this.listener = listener;
            this.userId = userId;
        }

        @Override
        public void binderDied() {
            synchronized (mLock) {
                mSession2TokensListenerRecords.remove(this);
            }
        }
    }

    final class SettingsObserver extends ContentObserver {
        private final Uri mSecureSettingsUri = Settings.Secure.getUriFor(
                Settings.Secure.ENABLED_NOTIFICATION_LISTENERS);

        private SettingsObserver() {
            super(null);
        }

        private void observe() {
            mContentResolver.registerContentObserver(mSecureSettingsUri,
                    false, this, USER_ALL);
        }

        @Override
        public void onChange(boolean selfChange, Uri uri) {
            updateActiveSessionListeners();
        }
    }

    class SessionManagerImpl extends ISessionManager.Stub {
        private static final String EXTRA_WAKELOCK_ACQUIRED =
                "android.media.AudioService.WAKELOCK_ACQUIRED";
        private static final int WAKELOCK_RELEASE_ON_FINISHED = 1980; // magic number

        private boolean mVoiceButtonDown = false;
        private boolean mVoiceButtonHandled = false;

        @Override
        public ISession createSession(String packageName, ISessionCallback cb, String tag,
                Bundle sessionInfo, int userId) throws RemoteException {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();
            try {
                enforcePackageName(packageName, uid);
                int resolvedUserId = ActivityManager.handleIncomingUser(pid, uid, userId,
                        false /* allowAll */, true /* requireFull */, "createSession", packageName);
                if (cb == null) {
                    throw new IllegalArgumentException("Controller callback cannot be null");
                }
                return createSessionInternal(pid, uid, resolvedUserId, packageName, cb, tag,
                        sessionInfo).getSessionBinder();
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public void notifySession2Created(Session2Token sessionToken) throws RemoteException {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();
            try {
                if (DEBUG) {
                    Log.d(TAG, "Session2 is created " + sessionToken);
                }
                if (uid != sessionToken.getUid()) {
                    throw new SecurityException("Unexpected Session2Token's UID, expected=" + uid
                            + " but actually=" + sessionToken.getUid());
                }
                Controller2Callback callback = new Controller2Callback(sessionToken);
                // Note: It's safe not to keep controller here because it wouldn't be GC'ed until
                //       it's closed.
                // TODO: Keep controller as well for better readability
                //       because the GC behavior isn't straightforward.
                MediaController2 controller = new MediaController2.Builder(mContext, sessionToken)
                        .setControllerCallback(new HandlerExecutor(mHandler), callback)
                        .build();
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public List<MediaSession.Token> getSessions(ComponentName componentName, int userId) {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();

            try {
                int resolvedUserId = verifySessionsRequest(componentName, userId, pid, uid);
                ArrayList<MediaSession.Token> tokens = new ArrayList<>();
                synchronized (mLock) {
                    List<MediaSessionRecord> records = getActiveSessionsLocked(resolvedUserId);
                    for (MediaSessionRecord record : records) {
                        tokens.add(record.getSessionToken());
                    }
                }
                return tokens;
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public ParceledListSlice getSession2Tokens(int userId) {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();

            try {
                // Check that they can make calls on behalf of the user and
                // get the final user id
                int resolvedUserId = ActivityManager.handleIncomingUser(pid, uid, userId,
                        true /* allowAll */, true /* requireFull */, "getSession2Tokens",
                        null /* optional packageName */);
                List<Session2Token> result;
                synchronized (mLock) {
                    result = getSession2TokensLocked(resolvedUserId);
                }
                return new ParceledListSlice(result);
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public void addSessionsListener(IActiveSessionsListener listener,
                ComponentName componentName, int userId) throws RemoteException {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();

            try {
                int resolvedUserId = verifySessionsRequest(componentName, userId, pid, uid);
                synchronized (mLock) {
                    int index = findIndexOfSessionsListenerLocked(listener);
                    if (index != -1) {
                        Log.w(TAG, "ActiveSessionsListener is already added, ignoring");
                        return;
                    }
                    SessionsListenerRecord record = new SessionsListenerRecord(listener,
                            componentName, resolvedUserId, pid, uid);
                    try {
                        listener.asBinder().linkToDeath(record, 0);
                    } catch (RemoteException e) {
                        Log.e(TAG, "ActiveSessionsListener is dead, ignoring it", e);
                        return;
                    }
                    mSessionsListeners.add(record);
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public void removeSessionsListener(IActiveSessionsListener listener)
                throws RemoteException {
            synchronized (mLock) {
                int index = findIndexOfSessionsListenerLocked(listener);
                if (index != -1) {
                    SessionsListenerRecord record = mSessionsListeners.remove(index);
                    try {
                        record.listener.asBinder().unlinkToDeath(record, 0);
                    } catch (Exception e) {
                        // ignore exceptions, the record is being removed
                    }
                }
            }
        }

        @Override
        public void addSession2TokensListener(ISession2TokensListener listener,
                int userId) {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();

            try {
                // Check that they can make calls on behalf of the user and get the final user id.
                int resolvedUserId = ActivityManager.handleIncomingUser(pid, uid, userId,
                        true /* allowAll */, true /* requireFull */, "addSession2TokensListener",
                        null /* optional packageName */);
                synchronized (mLock) {
                    int index = findIndexOfSession2TokensListenerLocked(listener);
                    if (index >= 0) {
                        Log.w(TAG, "addSession2TokensListener is already added, ignoring");
                        return;
                    }
                    mSession2TokensListenerRecords.add(
                            new Session2TokensListenerRecord(listener, resolvedUserId));
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public void removeSession2TokensListener(ISession2TokensListener listener) {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();

            try {
                synchronized (mLock) {
                    int index = findIndexOfSession2TokensListenerLocked(listener);
                    if (index >= 0) {
                        Session2TokensListenerRecord listenerRecord =
                                mSession2TokensListenerRecords.remove(index);
                        try {
                            listenerRecord.listener.asBinder().unlinkToDeath(listenerRecord, 0);
                        } catch (Exception e) {
                            // Ignore exception.
                        }
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        /**
         * Handles the dispatching of the media button events to one of the
         * registered listeners, or if there was none, broadcast an
         * ACTION_MEDIA_BUTTON intent to the rest of the system.
         *
         * @param packageName The caller package
         * @param asSystemService {@code true} if the event sent to the session as if it was come
         *          from the system service instead of the app process. This helps sessions to
         *          distinguish between the key injection by the app and key events from the
         *          hardware devices. Should be used only when the volume key events aren't handled
         *          by foreground activity. {@code false} otherwise to tell session about the real
         *          caller.
         * @param keyEvent a non-null KeyEvent whose key code is one of the
         *            supported media buttons
         * @param needWakeLock true if a PARTIAL_WAKE_LOCK needs to be held
         *            while this key event is dispatched.
         */
        @Override
        public void dispatchMediaKeyEvent(String packageName, boolean asSystemService,
                KeyEvent keyEvent, boolean needWakeLock) {
            if (keyEvent == null || !KeyEvent.isMediaSessionKey(keyEvent.getKeyCode())) {
                Log.w(TAG, "Attempted to dispatch null or non-media key event.");
                return;
            }

            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();
            try {
                if (DEBUG) {
                    Log.d(TAG, "dispatchMediaKeyEvent, pkg=" + packageName + " pid=" + pid
                            + ", uid=" + uid + ", asSystem=" + asSystemService + ", event="
                            + keyEvent);
                }
                if (!isUserSetupComplete()) {
                    // Global media key handling can have the side-effect of starting new
                    // activities which is undesirable while setup is in progress.
                    Slog.i(TAG, "Not dispatching media key event because user "
                            + "setup is in progress.");
                    return;
                }

                synchronized (mLock) {
                    boolean isGlobalPriorityActive = isGlobalPriorityActiveLocked();
                    if (isGlobalPriorityActive && uid != Process.SYSTEM_UID) {
                        // Prevent dispatching key event through reflection while the global
                        // priority session is active.
                        Slog.i(TAG, "Only the system can dispatch media key event "
                                + "to the global priority session.");
                        return;
                    }
                    if (!isGlobalPriorityActive) {
                        if (mCurrentFullUserRecord.mOnMediaKeyListener != null) {
                            if (DEBUG_KEY_EVENT) {
                                Log.d(TAG, "Send " + keyEvent + " to the media key listener");
                            }
                            try {
                                mCurrentFullUserRecord.mOnMediaKeyListener.onMediaKey(keyEvent,
                                        new MediaKeyListenerResultReceiver(packageName, pid, uid,
                                                asSystemService, keyEvent, needWakeLock));
                                return;
                            } catch (RemoteException e) {
                                Log.w(TAG, "Failed to send " + keyEvent
                                        + " to the media key listener");
                            }
                        }
                    }
                    if (!isGlobalPriorityActive && isVoiceKey(keyEvent.getKeyCode())) {
                        handleVoiceKeyEventLocked(packageName, pid, uid, asSystemService, keyEvent,
                                needWakeLock);
                    } else {
                        dispatchMediaKeyEventLocked(packageName, pid, uid, asSystemService,
                                keyEvent, needWakeLock);
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public boolean dispatchMediaKeyEventToSessionAsSystemService(String packageName,
                MediaSession.Token sessionToken, KeyEvent keyEvent) {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();
            try {
                synchronized (mLock) {
                    MediaSessionRecord record = getMediaSessionRecordLocked(sessionToken);
                    if (record == null) {
                        if (DEBUG) {
                            Log.d(TAG, "Failed to find session to dispatch key event.");
                        }
                        return false;
                    }
                    if (DEBUG) {
                        Log.d(TAG, "dispatchMediaKeyEventToSessionAsSystemService, pkg="
                                + packageName + ", pid=" + pid + ", uid=" + uid + ", sessionToken="
                                + sessionToken + ", event=" + keyEvent + ", session=" + record);
                    }
                    return record.sendMediaButton(packageName, pid, uid, true /* asSystemService */,
                            keyEvent, 0, null);
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public void setCallback(ICallback callback) {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();
            try {
                if (!UserHandle.isSameApp(uid, Process.BLUETOOTH_UID)) {
                    throw new SecurityException("Only Bluetooth service processes can set"
                            + " Callback");
                }
                synchronized (mLock) {
                    int userId = UserHandle.getUserId(uid);
                    FullUserRecord user = getFullUserRecordLocked(userId);
                    if (user == null || user.mFullUserId != userId) {
                        Log.w(TAG, "Only the full user can set the callback"
                                + ", userId=" + userId);
                        return;
                    }
                    user.mCallback = callback;
                    Log.d(TAG, "The callback " + user.mCallback
                            + " is set by " + getCallingPackageName(uid));
                    if (user.mCallback == null) {
                        return;
                    }
                    try {
                        user.mCallback.asBinder().linkToDeath(
                                new IBinder.DeathRecipient() {
                                    @Override
                                    public void binderDied() {
                                        synchronized (mLock) {
                                            user.mCallback = null;
                                        }
                                    }
                                }, 0);
                        user.pushAddressedPlayerChangedLocked();
                    } catch (RemoteException e) {
                        Log.w(TAG, "Failed to set callback", e);
                        user.mCallback = null;
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public void setOnVolumeKeyLongPressListener(IOnVolumeKeyLongPressListener listener) {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();
            try {
                // Enforce SET_VOLUME_KEY_LONG_PRESS_LISTENER permission.
                if (mContext.checkPermission(
                        android.Manifest.permission.SET_VOLUME_KEY_LONG_PRESS_LISTENER, pid, uid)
                        != PackageManager.PERMISSION_GRANTED) {
                    throw new SecurityException("Must hold the SET_VOLUME_KEY_LONG_PRESS_LISTENER"
                            + " permission.");
                }

                synchronized (mLock) {
                    int userId = UserHandle.getUserId(uid);
                    FullUserRecord user = getFullUserRecordLocked(userId);
                    if (user == null || user.mFullUserId != userId) {
                        Log.w(TAG, "Only the full user can set the volume key long-press listener"
                                + ", userId=" + userId);
                        return;
                    }
                    if (user.mOnVolumeKeyLongPressListener != null
                            && user.mOnVolumeKeyLongPressListenerUid != uid) {
                        Log.w(TAG, "The volume key long-press listener cannot be reset"
                                + " by another app , mOnVolumeKeyLongPressListener="
                                + user.mOnVolumeKeyLongPressListenerUid
                                + ", uid=" + uid);
                        return;
                    }

                    user.mOnVolumeKeyLongPressListener = listener;
                    user.mOnVolumeKeyLongPressListenerUid = uid;

                    Log.d(TAG, "The volume key long-press listener "
                            + listener + " is set by " + getCallingPackageName(uid));

                    if (user.mOnVolumeKeyLongPressListener != null) {
                        try {
                            user.mOnVolumeKeyLongPressListener.asBinder().linkToDeath(
                                    new IBinder.DeathRecipient() {
                                        @Override
                                        public void binderDied() {
                                            synchronized (mLock) {
                                                user.mOnVolumeKeyLongPressListener = null;
                                            }
                                        }
                                    }, 0);
                        } catch (RemoteException e) {
                            Log.w(TAG, "Failed to set death recipient "
                                    + user.mOnVolumeKeyLongPressListener);
                            user.mOnVolumeKeyLongPressListener = null;
                        }
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public void setOnMediaKeyListener(IOnMediaKeyListener listener) {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();
            try {
                // Enforce SET_MEDIA_KEY_LISTENER permission.
                if (mContext.checkPermission(
                        android.Manifest.permission.SET_MEDIA_KEY_LISTENER, pid, uid)
                        != PackageManager.PERMISSION_GRANTED) {
                    throw new SecurityException("Must hold the SET_MEDIA_KEY_LISTENER permission.");
                }

                synchronized (mLock) {
                    int userId = UserHandle.getUserId(uid);
                    FullUserRecord user = getFullUserRecordLocked(userId);
                    if (user == null || user.mFullUserId != userId) {
                        Log.w(TAG, "Only the full user can set the media key listener"
                                + ", userId=" + userId);
                        return;
                    }
                    if (user.mOnMediaKeyListener != null && user.mOnMediaKeyListenerUid != uid) {
                        Log.w(TAG, "The media key listener cannot be reset by another app. "
                                + ", mOnMediaKeyListenerUid=" + user.mOnMediaKeyListenerUid
                                + ", uid=" + uid);
                        return;
                    }

                    user.mOnMediaKeyListener = listener;
                    user.mOnMediaKeyListenerUid = uid;

                    Log.d(TAG, "The media key listener " + user.mOnMediaKeyListener
                            + " is set by " + getCallingPackageName(uid));

                    if (user.mOnMediaKeyListener != null) {
                        try {
                            user.mOnMediaKeyListener.asBinder().linkToDeath(
                                    new IBinder.DeathRecipient() {
                                        @Override
                                        public void binderDied() {
                                            synchronized (mLock) {
                                                user.mOnMediaKeyListener = null;
                                            }
                                        }
                                    }, 0);
                        } catch (RemoteException e) {
                            Log.w(TAG, "Failed to set death recipient " + user.mOnMediaKeyListener);
                            user.mOnMediaKeyListener = null;
                        }
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        /**
         * Handles the dispatching of the volume button events to one of the
         * registered listeners. If there's a volume key long-press listener and
         * there's no active global priority session, long-pressess will be sent to the
         * long-press listener instead of adjusting volume.
         *
         * @param packageName The caller's package name, obtained by Context#getPackageName()
         * @param opPackageName The caller's op package name, obtained by Context#getOpPackageName()
         * @param asSystemService {@code true} if the event sent to the session as if it was come
         *          from the system service instead of the app process. This helps sessions to
         *          distinguish between the key injection by the app and key events from the
         *          hardware devices. Should be used only when the volume key events aren't handled
         *          by foreground activity. {@code false} otherwise to tell session about the real
         *          caller.
         * @param keyEvent a non-null KeyEvent whose key code is one of the
         *            {@link KeyEvent#KEYCODE_VOLUME_UP},
         *            {@link KeyEvent#KEYCODE_VOLUME_DOWN},
         *            or {@link KeyEvent#KEYCODE_VOLUME_MUTE}.
         * @param stream stream type to adjust volume.
         * @param musicOnly true if both UI nor haptic feedback aren't needed when adjust volume.
         */
        @Override
        public void dispatchVolumeKeyEvent(String packageName, String opPackageName,
                boolean asSystemService, KeyEvent keyEvent, int stream, boolean musicOnly) {
            if (keyEvent == null
                    || (keyEvent.getKeyCode() != KeyEvent.KEYCODE_VOLUME_UP
                    && keyEvent.getKeyCode() != KeyEvent.KEYCODE_VOLUME_DOWN
                    && keyEvent.getKeyCode() != KeyEvent.KEYCODE_VOLUME_MUTE)) {
                Log.w(TAG, "Attempted to dispatch null or non-volume key event.");
                return;
            }

            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();

            if (DEBUG_KEY_EVENT) {
                Log.d(TAG, "dispatchVolumeKeyEvent, pkg=" + packageName
                        + ", opPkg=" + opPackageName + ", pid=" + pid + ", uid=" + uid
                        + ", asSystem=" + asSystemService + ", event=" + keyEvent
                        + ", stream=" + stream + ", musicOnly=" + musicOnly);
            }

            try {
                synchronized (mLock) {
                    if (isGlobalPriorityActiveLocked()
                            || mCurrentFullUserRecord.mOnVolumeKeyLongPressListener == null) {
                        dispatchVolumeKeyEventLocked(packageName, opPackageName, pid, uid,
                                asSystemService, keyEvent, stream, musicOnly);
                    } else {
                        // TODO: Consider the case when both volume up and down keys are pressed
                        //       at the same time.
                        if (keyEvent.getAction() == KeyEvent.ACTION_DOWN) {
                            if (keyEvent.getRepeatCount() == 0) {
                                // Keeps the copy of the KeyEvent because it can be reused.
                                mCurrentFullUserRecord.mInitialDownVolumeKeyEvent =
                                        KeyEvent.obtain(keyEvent);
                                mCurrentFullUserRecord.mInitialDownVolumeStream = stream;
                                mCurrentFullUserRecord.mInitialDownMusicOnly = musicOnly;
                                mHandler.sendMessageDelayed(
                                        mHandler.obtainMessage(
                                                MessageHandler.MSG_VOLUME_INITIAL_DOWN,
                                                mCurrentFullUserRecord.mFullUserId, 0),
                                        mLongPressTimeout);
                            }
                            if (keyEvent.getRepeatCount() > 0 || keyEvent.isLongPress()) {
                                mHandler.removeMessages(MessageHandler.MSG_VOLUME_INITIAL_DOWN);
                                if (mCurrentFullUserRecord.mInitialDownVolumeKeyEvent != null) {
                                    dispatchVolumeKeyLongPressLocked(
                                            mCurrentFullUserRecord.mInitialDownVolumeKeyEvent);
                                    // Mark that the key is already handled.
                                    mCurrentFullUserRecord.mInitialDownVolumeKeyEvent = null;
                                }
                                dispatchVolumeKeyLongPressLocked(keyEvent);
                            }
                        } else { // if up
                            mHandler.removeMessages(MessageHandler.MSG_VOLUME_INITIAL_DOWN);
                            if (mCurrentFullUserRecord.mInitialDownVolumeKeyEvent != null
                                    && mCurrentFullUserRecord.mInitialDownVolumeKeyEvent
                                    .getDownTime() == keyEvent.getDownTime()) {
                                // Short-press. Should change volume.
                                dispatchVolumeKeyEventLocked(packageName, opPackageName, pid, uid,
                                        asSystemService,
                                        mCurrentFullUserRecord.mInitialDownVolumeKeyEvent,
                                        mCurrentFullUserRecord.mInitialDownVolumeStream,
                                        mCurrentFullUserRecord.mInitialDownMusicOnly);
                                dispatchVolumeKeyEventLocked(packageName, opPackageName, pid, uid,
                                        asSystemService, keyEvent, stream, musicOnly);
                            } else {
                                dispatchVolumeKeyLongPressLocked(keyEvent);
                            }
                        }
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        private void dispatchVolumeKeyEventLocked(String packageName, String opPackageName, int pid,
                int uid, boolean asSystemService, KeyEvent keyEvent, int stream,
                boolean musicOnly) {
            boolean down = keyEvent.getAction() == KeyEvent.ACTION_DOWN;
            boolean up = keyEvent.getAction() == KeyEvent.ACTION_UP;
            int direction = 0;
            boolean isMute = false;
            switch (keyEvent.getKeyCode()) {
                case KeyEvent.KEYCODE_VOLUME_UP:
                    direction = AudioManager.ADJUST_RAISE;
                    break;
                case KeyEvent.KEYCODE_VOLUME_DOWN:
                    direction = AudioManager.ADJUST_LOWER;
                    break;
                case KeyEvent.KEYCODE_VOLUME_MUTE:
                    isMute = true;
                    break;
            }
            if (down || up) {
                int flags = AudioManager.FLAG_FROM_KEY;
                if (musicOnly) {
                    // This flag is used when the screen is off to only affect active media.
                    flags |= AudioManager.FLAG_ACTIVE_MEDIA_ONLY;
                } else {
                    // These flags are consistent with the home screen
                    if (up) {
                        flags |= AudioManager.FLAG_PLAY_SOUND | AudioManager.FLAG_VIBRATE;
                    } else {
                        flags |= AudioManager.FLAG_SHOW_UI | AudioManager.FLAG_VIBRATE;
                    }
                }
                if (direction != 0) {
                    // If this is action up we want to send a beep for non-music events
                    if (up) {
                        direction = 0;
                    }
                    dispatchAdjustVolumeLocked(packageName, opPackageName, pid, uid,
                            asSystemService, stream, direction, flags);
                } else if (isMute) {
                    if (down && keyEvent.getRepeatCount() == 0) {
                        dispatchAdjustVolumeLocked(packageName, opPackageName, pid, uid,
                                asSystemService, stream, AudioManager.ADJUST_TOGGLE_MUTE, flags);
                    }
                }
            }
        }

        @Override
        public void dispatchVolumeKeyEventToSessionAsSystemService(String packageName,
                String opPackageName, MediaSession.Token sessionToken, KeyEvent keyEvent) {
            int pid = Binder.getCallingPid();
            int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();
            try {
                synchronized (mLock) {
                    MediaSessionRecord record = getMediaSessionRecordLocked(sessionToken);
                    if (record == null) {
                        if (DEBUG) {
                            Log.d(TAG, "Failed to find session to dispatch key event.");
                        }
                        return;
                    }
                    if (DEBUG) {
                        Log.d(TAG, "dispatchVolumeKeyEventToSessionAsSystemService, pkg="
                                + packageName + ", opPkg=" + opPackageName + ", pid=" + pid
                                + ", uid=" + uid + ", sessionToken=" + sessionToken + ", event="
                                + keyEvent + ", session=" + record);
                    }
                    switch (keyEvent.getAction()) {
                        case KeyEvent.ACTION_DOWN: {
                            int direction = 0;
                            switch (keyEvent.getKeyCode()) {
                                case KeyEvent.KEYCODE_VOLUME_UP:
                                    direction = AudioManager.ADJUST_RAISE;
                                    break;
                                case KeyEvent.KEYCODE_VOLUME_DOWN:
                                    direction = AudioManager.ADJUST_LOWER;
                                    break;
                                case KeyEvent.KEYCODE_VOLUME_MUTE:
                                    direction = AudioManager.ADJUST_TOGGLE_MUTE;
                                    break;
                            }
                            record.adjustVolume(packageName, opPackageName, pid, uid,
                                    null /* caller */, true /* asSystemService */, direction,
                                    AudioManager.FLAG_SHOW_UI, false /* useSuggested */);
                            break;
                        }

                        case KeyEvent.ACTION_UP: {
                            final int flags =
                                    AudioManager.FLAG_PLAY_SOUND | AudioManager.FLAG_VIBRATE
                                            | AudioManager.FLAG_FROM_KEY;
                            record.adjustVolume(packageName, opPackageName, pid, uid,
                                    null /* caller */, true /* asSystemService */, 0,
                                    flags, false /* useSuggested */);
                        }
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public void dispatchAdjustVolume(String packageName, String opPackageName,
                int suggestedStream, int delta, int flags) {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();
            try {
                synchronized (mLock) {
                    dispatchAdjustVolumeLocked(packageName, opPackageName, pid, uid, false,
                            suggestedStream, delta, flags);
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        @Override
        public void registerRemoteVolumeController(IRemoteVolumeController rvc) {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();
            synchronized (mLock) {
                try {
                    enforceStatusBarServicePermission("listen for volume changes", pid, uid);
                    mRemoteVolumeControllers.register(rvc);
                } finally {
                    Binder.restoreCallingIdentity(token);
                }
            }
        }

        @Override
        public void unregisterRemoteVolumeController(IRemoteVolumeController rvc) {
            final int pid = Binder.getCallingPid();
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();
            synchronized (mLock) {
                try {
                    enforceStatusBarServicePermission("listen for volume changes", pid, uid);
                    mRemoteVolumeControllers.unregister(rvc);
                } finally {
                    Binder.restoreCallingIdentity(token);
                }
            }
        }

        @Override
        public boolean isGlobalPriorityActive() {
            synchronized (mLock) {
                return isGlobalPriorityActiveLocked();
            }
        }

        @Override
        public void dump(FileDescriptor fd, final PrintWriter pw, String[] args) {
            if (!DumpUtils.checkDumpPermission(mContext, TAG, pw)) return;

            pw.println("MEDIA SESSION SERVICE (dumpsys media_session)");
            pw.println();

            synchronized (mLock) {
                pw.println(mSessionsListeners.size() + " sessions listeners.");
                pw.println("Global priority session is " + mGlobalPrioritySession);
                if (mGlobalPrioritySession != null) {
                    mGlobalPrioritySession.dump(pw, "  ");
                }
                pw.println("User Records:");
                int count = mUserRecords.size();
                for (int i = 0; i < count; i++) {
                    mUserRecords.valueAt(i).dumpLocked(pw, "");
                }
                mAudioPlayerStateMonitor.dump(mContext, pw, "");
            }
        }

        /**
         * Returns if the controller's package is trusted (i.e. has either MEDIA_CONTENT_CONTROL
         * permission or an enabled notification listener)
         *
         * @param controllerPackageName package name of the controller app
         * @param controllerPid pid of the controller app
         * @param controllerUid uid of the controller app
         */
        @Override
        public boolean isTrusted(String controllerPackageName, int controllerPid, int controllerUid)
                throws RemoteException {
            final int uid = Binder.getCallingUid();
            final long token = Binder.clearCallingIdentity();
            try {
                // Don't perform sanity check between controllerPackageName and controllerUid.
                // When an (activity|service) runs on the another apps process by specifying
                // android:process in the AndroidManifest.xml, then PID and UID would have the
                // running process' information instead of the (activity|service) that has created
                // MediaController.
                // Note that we can use Context#getOpPackageName() instead of
                // Context#getPackageName() for getting package name that matches with the PID/UID,
                // but it doesn't tell which package has created the MediaController, so useless.
                return hasMediaControlPermission(UserHandle.getUserId(uid), controllerPackageName,
                        controllerPid, controllerUid);
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

        // For MediaSession
        private int verifySessionsRequest(ComponentName componentName, int userId, final int pid,
                final int uid) {
            String packageName = null;
            if (componentName != null) {
                // If they gave us a component name verify they own the
                // package
                packageName = componentName.getPackageName();
                enforcePackageName(packageName, uid);
            }
            // Check that they can make calls on behalf of the user and
            // get the final user id
            int resolvedUserId = ActivityManager.handleIncomingUser(pid, uid, userId,
                    true /* allowAll */, true /* requireFull */, "getSessions", packageName);
            // Check if they have the permissions or their component is
            // enabled for the user they're calling from.
            enforceMediaPermissions(componentName, pid, uid, resolvedUserId);
            return resolvedUserId;
        }

        private boolean hasMediaControlPermission(int resolvedUserId, String packageName,
                int pid, int uid) throws RemoteException {
            // Allow API calls from the System UI and Settings
            if (hasStatusBarServicePermission(pid, uid)) {
                return true;
            }

            // Check if it's system server or has MEDIA_CONTENT_CONTROL.
            // Note that system server doesn't have MEDIA_CONTENT_CONTROL, so we need extra
            // check here.
            if (uid == Process.SYSTEM_UID || mContext.checkPermission(
                    android.Manifest.permission.MEDIA_CONTENT_CONTROL, pid, uid)
                    == PackageManager.PERMISSION_GRANTED) {
                return true;
            } else if (DEBUG) {
                Log.d(TAG, packageName + " (uid=" + uid + ") hasn't granted MEDIA_CONTENT_CONTROL");
            }

            // You may not access another user's content as an enabled listener.
            final int userId = UserHandle.getUserId(uid);
            if (resolvedUserId != userId) {
                return false;
            }

            // TODO(jaewan): (Post-P) Propose NotificationManager#hasEnabledNotificationListener(
            //               String pkgName) to notification team for optimization
            final List<ComponentName> enabledNotificationListeners =
                    mNotificationManager.getEnabledNotificationListeners(userId);
            if (enabledNotificationListeners != null) {
                for (int i = 0; i < enabledNotificationListeners.size(); i++) {
                    if (TextUtils.equals(packageName,
                            enabledNotificationListeners.get(i).getPackageName())) {
                        return true;
                    }
                }
            }
            if (DEBUG) {
                Log.d(TAG, packageName + " (uid=" + uid + ") doesn't have an enabled "
                        + "notification listener");
            }
            return false;
        }

        private void dispatchAdjustVolumeLocked(String packageName, String opPackageName, int pid,
                int uid, boolean asSystemService, int suggestedStream, int direction, int flags) {
            MediaSessionRecord session = isGlobalPriorityActiveLocked() ? mGlobalPrioritySession
                    : mCurrentFullUserRecord.mPriorityStack.getDefaultVolumeSession();

            boolean preferSuggestedStream = false;
            if (isValidLocalStreamType(suggestedStream)
                    && AudioSystem.isStreamActive(suggestedStream, 0)) {
                preferSuggestedStream = true;
            }
            if (DEBUG_KEY_EVENT) {
                Log.d(TAG, "Adjusting " + session + " by " + direction + ". flags="
                        + flags + ", suggestedStream=" + suggestedStream
                        + ", preferSuggestedStream=" + preferSuggestedStream);
            }
            if (session == null || preferSuggestedStream) {
                if ((flags & AudioManager.FLAG_ACTIVE_MEDIA_ONLY) != 0
                        && !AudioSystem.isStreamActive(AudioManager.STREAM_MUSIC, 0)) {
                    if (DEBUG) {
                        Log.d(TAG, "No active session to adjust, skipping media only volume event");
                    }
                    return;
                }

                // Execute mAudioService.adjustSuggestedStreamVolume() on
                // handler thread of MediaSessionService.
                // This will release the MediaSessionService.mLock sooner and avoid
                // a potential deadlock between MediaSessionService.mLock and
                // ActivityManagerService lock.
                mHandler.post(new Runnable() {
                    @Override
                    public void run() {
                        final String callingOpPackageName;
                        final int callingUid;
                        if (asSystemService) {
                            callingOpPackageName = mContext.getOpPackageName();
                            callingUid = Process.myUid();
                        } else {
                            callingOpPackageName = opPackageName;
                            callingUid = uid;
                        }
                        try {
                            mAudioManagerInternal.adjustSuggestedStreamVolumeForUid(suggestedStream,
                                    direction, flags, callingOpPackageName, callingUid);
                        } catch (SecurityException | IllegalArgumentException e) {
                            Log.e(TAG, "Cannot adjust volume: direction=" + direction
                                    + ", suggestedStream=" + suggestedStream + ", flags=" + flags
                                    + ", packageName=" + packageName + ", uid=" + uid
                                    + ", asSystemService=" + asSystemService, e);
                        }
                    }
                });
            } else {
                session.adjustVolume(packageName, opPackageName, pid, uid, null, asSystemService,
                        direction, flags, true);
            }
        }

        private void handleVoiceKeyEventLocked(String packageName, int pid, int uid,
                boolean asSystemService, KeyEvent keyEvent, boolean needWakeLock) {
            int action = keyEvent.getAction();
            boolean isLongPress = (keyEvent.getFlags() & KeyEvent.FLAG_LONG_PRESS) != 0;
            if (action == KeyEvent.ACTION_DOWN) {
                if (keyEvent.getRepeatCount() == 0) {
                    mVoiceButtonDown = true;
                    mVoiceButtonHandled = false;
                } else if (mVoiceButtonDown && !mVoiceButtonHandled && isLongPress) {
                    mVoiceButtonHandled = true;
                    startVoiceInput(needWakeLock);
                }
            } else if (action == KeyEvent.ACTION_UP) {
                if (mVoiceButtonDown) {
                    mVoiceButtonDown = false;
                    if (!mVoiceButtonHandled && !keyEvent.isCanceled()) {
                        // Resend the down then send this event through
                        KeyEvent downEvent = KeyEvent.changeAction(keyEvent, KeyEvent.ACTION_DOWN);
                        dispatchMediaKeyEventLocked(packageName, pid, uid, asSystemService,
                                downEvent, needWakeLock);
                        dispatchMediaKeyEventLocked(packageName, pid, uid, asSystemService,
                                keyEvent, needWakeLock);
                    }
                }
            }
        }

        private void dispatchMediaKeyEventLocked(String packageName, int pid, int uid,
                boolean asSystemService, KeyEvent keyEvent, boolean needWakeLock) {
            MediaSessionRecord session = mCurrentFullUserRecord.getMediaButtonSessionLocked();
            if (session != null) {
                if (DEBUG_KEY_EVENT) {
                    Log.d(TAG, "Sending " + keyEvent + " to " + session);
                }
                if (needWakeLock) {
                    mKeyEventReceiver.aquireWakeLockLocked();
                }
                // If we don't need a wakelock use -1 as the id so we won't release it later.
                session.sendMediaButton(packageName, pid, uid, asSystemService, keyEvent,
                        needWakeLock ? mKeyEventReceiver.mLastTimeoutId : -1,
                        mKeyEventReceiver);
                if (mCurrentFullUserRecord.mCallback != null) {
                    try {
                        mCurrentFullUserRecord.mCallback.onMediaKeyEventDispatchedToMediaSession(
                                keyEvent, session.getSessionToken());
                    } catch (RemoteException e) {
                        Log.w(TAG, "Failed to send callback", e);
                    }
                }
            } else if (mCurrentFullUserRecord.mLastMediaButtonReceiver != null
                    || mCurrentFullUserRecord.mRestoredMediaButtonReceiver != null) {
                if (needWakeLock) {
                    mKeyEventReceiver.aquireWakeLockLocked();
                }
                Intent mediaButtonIntent = new Intent(Intent.ACTION_MEDIA_BUTTON);
                mediaButtonIntent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
                mediaButtonIntent.putExtra(Intent.EXTRA_KEY_EVENT, keyEvent);
                // TODO: Find a way to also send PID/UID in secure way.
                String callerPackageName =
                        (asSystemService) ? mContext.getPackageName() : packageName;
                mediaButtonIntent.putExtra(Intent.EXTRA_PACKAGE_NAME, callerPackageName);
                try {
                    if (mCurrentFullUserRecord.mLastMediaButtonReceiver != null) {
                        PendingIntent receiver = mCurrentFullUserRecord.mLastMediaButtonReceiver;
                        if (DEBUG_KEY_EVENT) {
                            Log.d(TAG, "Sending " + keyEvent
                                    + " to the last known PendingIntent " + receiver);
                        }
                        receiver.send(mContext,
                                needWakeLock ? mKeyEventReceiver.mLastTimeoutId : -1,
                                mediaButtonIntent, mKeyEventReceiver, mHandler);
                        if (mCurrentFullUserRecord.mCallback != null) {
                            ComponentName componentName = mCurrentFullUserRecord
                                    .mLastMediaButtonReceiver.getIntent().getComponent();
                            if (componentName != null) {
                                mCurrentFullUserRecord.mCallback
                                        .onMediaKeyEventDispatchedToMediaButtonReceiver(
                                                keyEvent, componentName);
                            }
                        }
                    } else {
                        ComponentName receiver =
                                mCurrentFullUserRecord.mRestoredMediaButtonReceiver;
                        int componentType = mCurrentFullUserRecord
                                .mRestoredMediaButtonReceiverComponentType;
                        UserHandle userHandle = UserHandle.of(mCurrentFullUserRecord
                                .mRestoredMediaButtonReceiverUserId);
                        if (DEBUG_KEY_EVENT) {
                            Log.d(TAG, "Sending " + keyEvent + " to the restored intent "
                                    + receiver + ", type=" + componentType);
                        }
                        mediaButtonIntent.setComponent(receiver);
                        try {
                            switch (componentType) {
                                case FullUserRecord.COMPONENT_TYPE_ACTIVITY:
                                    mContext.startActivityAsUser(mediaButtonIntent, userHandle);
                                    break;
                                case FullUserRecord.COMPONENT_TYPE_SERVICE:
                                    mContext.startForegroundServiceAsUser(mediaButtonIntent,
                                            userHandle);
                                    break;
                                default:
                                    // Legacy behavior for other cases.
                                    mContext.sendBroadcastAsUser(mediaButtonIntent, userHandle);
                            }
                        } catch (Exception e) {
                            Log.w(TAG, "Error sending media button to the restored intent "
                                    + receiver + ", type=" + componentType, e);
                        }
                        if (mCurrentFullUserRecord.mCallback != null) {
                            mCurrentFullUserRecord.mCallback
                                    .onMediaKeyEventDispatchedToMediaButtonReceiver(
                                            keyEvent, receiver);
                        }
                    }
                } catch (CanceledException e) {
                    Log.i(TAG, "Error sending key event to media button receiver "
                            + mCurrentFullUserRecord.mLastMediaButtonReceiver, e);
                } catch (RemoteException e) {
                    Log.w(TAG, "Failed to send callback", e);
                }
            }
        }

        private void startVoiceInput(boolean needWakeLock) {
            Intent voiceIntent = null;
            // select which type of search to launch:
            // - screen on and device unlocked: action is ACTION_WEB_SEARCH
            // - device locked or screen off: action is
            // ACTION_VOICE_SEARCH_HANDS_FREE
            // with EXTRA_SECURE set to true if the device is securely locked
            PowerManager pm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);
            boolean isLocked = mKeyguardManager != null && mKeyguardManager.isKeyguardLocked();
            if (!isLocked && pm.isScreenOn()) {
                voiceIntent = new Intent(android.speech.RecognizerIntent.ACTION_WEB_SEARCH);
                Log.i(TAG, "voice-based interactions: about to use ACTION_WEB_SEARCH");
            } else {
                voiceIntent = new Intent(RecognizerIntent.ACTION_VOICE_SEARCH_HANDS_FREE);
                voiceIntent.putExtra(RecognizerIntent.EXTRA_SECURE,
                        isLocked && mKeyguardManager.isKeyguardSecure());
                Log.i(TAG, "voice-based interactions: about to use ACTION_VOICE_SEARCH_HANDS_FREE");
            }
            // start the search activity
            if (needWakeLock) {
                mMediaEventWakeLock.acquire();
            }
            try {
                if (voiceIntent != null) {
                    voiceIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK
                            | Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);
                    if (DEBUG) Log.d(TAG, "voiceIntent: " + voiceIntent);
                    mContext.startActivityAsUser(voiceIntent, UserHandle.CURRENT);
                }
            } catch (ActivityNotFoundException e) {
                Log.w(TAG, "No activity for search: " + e);
            } finally {
                if (needWakeLock) {
                    mMediaEventWakeLock.release();
                }
            }
        }

        private boolean isVoiceKey(int keyCode) {
            return keyCode == KeyEvent.KEYCODE_HEADSETHOOK
                    || (!mHasFeatureLeanback && keyCode == KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE);
        }

        private boolean isUserSetupComplete() {
            return Settings.Secure.getIntForUser(mContext.getContentResolver(),
                    Settings.Secure.USER_SETUP_COMPLETE, 0, UserHandle.USER_CURRENT) != 0;
        }

        // we only handle public stream types, which are 0-5
        private boolean isValidLocalStreamType(int streamType) {
            return streamType >= AudioManager.STREAM_VOICE_CALL
                    && streamType <= AudioManager.STREAM_NOTIFICATION;
        }

        private class MediaKeyListenerResultReceiver extends ResultReceiver implements Runnable {
            private final String mPackageName;
            private final int mPid;
            private final int mUid;
            private final boolean mAsSystemService;
            private final KeyEvent mKeyEvent;
            private final boolean mNeedWakeLock;
            private boolean mHandled;

            private MediaKeyListenerResultReceiver(String packageName, int pid, int uid,
                    boolean asSystemService, KeyEvent keyEvent, boolean needWakeLock) {
                super(mHandler);
                mHandler.postDelayed(this, MEDIA_KEY_LISTENER_TIMEOUT);
                mPackageName = packageName;
                mPid = pid;
                mUid = uid;
                mAsSystemService = asSystemService;
                mKeyEvent = keyEvent;
                mNeedWakeLock = needWakeLock;
            }

            @Override
            public void run() {
                Log.d(TAG, "The media key listener is timed-out for " + mKeyEvent);
                dispatchMediaKeyEvent();
            }

            @Override
            protected void onReceiveResult(int resultCode, Bundle resultData) {
                if (resultCode == MediaSessionManager.RESULT_MEDIA_KEY_HANDLED) {
                    mHandled = true;
                    mHandler.removeCallbacks(this);
                    return;
                }
                dispatchMediaKeyEvent();
            }

            private void dispatchMediaKeyEvent() {
                if (mHandled) {
                    return;
                }
                mHandled = true;
                mHandler.removeCallbacks(this);
                synchronized (mLock) {
                    if (!isGlobalPriorityActiveLocked()
                            && isVoiceKey(mKeyEvent.getKeyCode())) {
                        handleVoiceKeyEventLocked(mPackageName, mPid, mUid, mAsSystemService,
                                mKeyEvent, mNeedWakeLock);
                    } else {
                        dispatchMediaKeyEventLocked(mPackageName, mPid, mUid, mAsSystemService,
                                mKeyEvent, mNeedWakeLock);
                    }
                }
            }
        }

        private KeyEventWakeLockReceiver mKeyEventReceiver = new KeyEventWakeLockReceiver(mHandler);

        class KeyEventWakeLockReceiver extends ResultReceiver implements Runnable,
                PendingIntent.OnFinished {
            private final Handler mHandler;
            private int mRefCount = 0;
            private int mLastTimeoutId = 0;

            KeyEventWakeLockReceiver(Handler handler) {
                super(handler);
                mHandler = handler;
            }

            public void onTimeout() {
                synchronized (mLock) {
                    if (mRefCount == 0) {
                        // We've already released it, so just return
                        return;
                    }
                    mLastTimeoutId++;
                    mRefCount = 0;
                    releaseWakeLockLocked();
                }
            }

            public void aquireWakeLockLocked() {
                if (mRefCount == 0) {
                    mMediaEventWakeLock.acquire();
                }
                mRefCount++;
                mHandler.removeCallbacks(this);
                mHandler.postDelayed(this, WAKELOCK_TIMEOUT);

            }

            @Override
            public void run() {
                onTimeout();
            }

            @Override
            protected void onReceiveResult(int resultCode, Bundle resultData) {
                if (resultCode < mLastTimeoutId) {
                    // Ignore results from calls that were before the last
                    // timeout, just in case.
                    return;
                } else {
                    synchronized (mLock) {
                        if (mRefCount > 0) {
                            mRefCount--;
                            if (mRefCount == 0) {
                                releaseWakeLockLocked();
                            }
                        }
                    }
                }
            }

            private void releaseWakeLockLocked() {
                mMediaEventWakeLock.release();
                mHandler.removeCallbacks(this);
            }

            @Override
            public void onSendFinished(PendingIntent pendingIntent, Intent intent, int resultCode,
                    String resultData, Bundle resultExtras) {
                onReceiveResult(resultCode, null);
            }
        };

        BroadcastReceiver mKeyEventDone = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                if (intent == null) {
                    return;
                }
                Bundle extras = intent.getExtras();
                if (extras == null) {
                    return;
                }
                synchronized (mLock) {
                    if (extras.containsKey(EXTRA_WAKELOCK_ACQUIRED)
                            && mMediaEventWakeLock.isHeld()) {
                        mMediaEventWakeLock.release();
                    }
                }
            }
        };
    }

    final class MessageHandler extends Handler {
        private static final int MSG_SESSIONS_CHANGED = 1;
        private static final int MSG_VOLUME_INITIAL_DOWN = 2;
        private final SparseArray<Integer> mIntegerCache = new SparseArray<>();

        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case MSG_SESSIONS_CHANGED:
                    pushSessionsChanged((int) msg.obj);
                    break;
                case MSG_VOLUME_INITIAL_DOWN:
                    synchronized (mLock) {
                        FullUserRecord user = mUserRecords.get((int) msg.arg1);
                        if (user != null && user.mInitialDownVolumeKeyEvent != null) {
                            dispatchVolumeKeyLongPressLocked(user.mInitialDownVolumeKeyEvent);
                            // Mark that the key is already handled.
                            user.mInitialDownVolumeKeyEvent = null;
                        }
                    }
                    break;
            }
        }

        public void postSessionsChanged(int userId) {
            // Use object instead of the arguments when posting message to remove pending requests.
            Integer userIdInteger = mIntegerCache.get(userId);
            if (userIdInteger == null) {
                userIdInteger = Integer.valueOf(userId);
                mIntegerCache.put(userId, userIdInteger);
            }
            removeMessages(MSG_SESSIONS_CHANGED, userIdInteger);
            obtainMessage(MSG_SESSIONS_CHANGED, userIdInteger).sendToTarget();
        }
    }

    private class Controller2Callback extends MediaController2.ControllerCallback {
        private final Session2Token mToken;

        Controller2Callback(Session2Token token) {
            mToken = token;
        }

        @Override
        public void onConnected(MediaController2 controller, Session2CommandGroup allowedCommands) {
            synchronized (mLock) {
                int userId = UserHandle.getUserId(mToken.getUid());
                mSession2TokensPerUser.get(userId).add(mToken);
                pushSession2TokensChangedLocked(userId);
            }
        }

        @Override
        public void onDisconnected(MediaController2 controller) {
            synchronized (mLock) {
                int userId = UserHandle.getUserId(mToken.getUid());
                mSession2TokensPerUser.get(userId).remove(mToken);
                pushSession2TokensChangedLocked(userId);
            }
        }
    }
}