diff --git a/services/core/java/com/android/server/MountService.java b/services/core/java/com/android/server/MountService.java
index 7ec9b82..d5f045e 100644
--- a/services/core/java/com/android/server/MountService.java
+++ b/services/core/java/com/android/server/MountService.java
@@ -201,8 +201,8 @@
     public static final String[] CRYPTO_TYPES
         = { "password", "default", "pattern", "pin" };
 
-    private Context mContext;
-    private NativeDaemonConnector mConnector;
+    private final Context mContext;
+    private final NativeDaemonConnector mConnector;
 
     private final Object mVolumesLock = new Object();
 
diff --git a/services/core/java/com/android/server/pm/BackgroundDexOptService.java b/services/core/java/com/android/server/pm/BackgroundDexOptService.java
new file mode 100644
index 0000000..f2db791
--- /dev/null
+++ b/services/core/java/com/android/server/pm/BackgroundDexOptService.java
@@ -0,0 +1,91 @@
+/*
+ * 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.pm;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.os.ServiceManager;
+import android.os.UserHandle;
+import android.util.Log;
+
+import java.util.HashSet;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * {@hide}
+ */
+public class BackgroundDexOptService {
+
+    static final String TAG = "BackgroundDexOptService";
+
+    private final BroadcastReceiver mIdleMaintenanceReceiver = new BroadcastReceiver() {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            String action = intent.getAction();
+            if (Intent.ACTION_IDLE_MAINTENANCE_START.equals(action)) {
+                onIdleStart();
+            } else if (Intent.ACTION_IDLE_MAINTENANCE_END.equals(action)) {
+                onIdleStop();
+            }
+        }
+    };
+
+    final PackageManagerService mPackageManager;
+
+    final AtomicBoolean mIdleTime = new AtomicBoolean(false);
+
+    public BackgroundDexOptService(Context context) {
+        mPackageManager = (PackageManagerService)ServiceManager.getService("package");
+
+        IntentFilter idleMaintenanceFilter = new IntentFilter();
+        idleMaintenanceFilter.addAction(Intent.ACTION_IDLE_MAINTENANCE_START);
+        idleMaintenanceFilter.addAction(Intent.ACTION_IDLE_MAINTENANCE_END);
+        context.registerReceiverAsUser(mIdleMaintenanceReceiver, UserHandle.ALL,
+                                       idleMaintenanceFilter, null, null);
+    }
+
+    public boolean onIdleStart() {
+        Log.i(TAG, "onIdleStart");
+        if (mPackageManager.isStorageLow()) {
+            return false;
+        }
+        final HashSet<String> pkgs = mPackageManager.getPackagesThatNeedDexOpt();
+        if (pkgs == null) {
+            return false;
+        }
+        mIdleTime.set(true);
+        new Thread("BackgroundDexOptService_DexOpter") {
+            @Override
+            public void run() {
+                for (String pkg : pkgs) {
+                    if (!mIdleTime.get()) {
+                        break;
+                    }
+                    mPackageManager.performDexOpt(pkg, false);
+                }
+            }
+        }.start();
+        return true;
+    }
+
+    public void onIdleStop() {
+        Log.i(TAG, "onIdleStop");
+        mIdleTime.set(false);
+    }
+}
diff --git a/services/core/java/com/android/server/pm/PackageManagerService.java b/services/core/java/com/android/server/pm/PackageManagerService.java
index 9804aee..c8b61f1 100755
--- a/services/core/java/com/android/server/pm/PackageManagerService.java
+++ b/services/core/java/com/android/server/pm/PackageManagerService.java
@@ -624,6 +624,7 @@
             }
             if (mBackgroundWriteRunning.compareAndSet(false, true)) {
                 new Thread("PackageUsage_DiskWriter") {
+                    @Override
                     public void run() {
                         try {
                             write(true);
@@ -1742,10 +1743,12 @@
         }
     }
 
+    @Override
     public boolean isFirstBoot() {
         return !mRestoredSettings;
     }
 
+    @Override
     public boolean isOnlyCoreApps() {
         return mOnlyCore;
     }
@@ -2042,6 +2045,7 @@
                 state, userId);
     }
 
+    @Override
     public boolean isPackageAvailable(String packageName, int userId) {
         if (!sUserManager.exists(userId)) return false;
         enforceCrossUserPermission(Binder.getCallingUid(), userId, false, "is package available");
@@ -2079,6 +2083,7 @@
         return null;
     }
 
+    @Override
     public String[] currentToCanonicalPackageNames(String[] names) {
         String[] out = new String[names.length];
         // reader
@@ -2091,6 +2096,7 @@
         return out;
     }
     
+    @Override
     public String[] canonicalToCurrentPackageNames(String[] names) {
         String[] out = new String[names.length];
         // reader
@@ -2151,6 +2157,7 @@
         return pi;
     }
     
+    @Override
     public PermissionInfo getPermissionInfo(String name, int flags) {
         // reader
         synchronized (mPackages) {
@@ -2162,6 +2169,7 @@
         }
     }
 
+    @Override
     public List<PermissionInfo> queryPermissionsByGroup(String group, int flags) {
         // reader
         synchronized (mPackages) {
@@ -2185,6 +2193,7 @@
         }
     }
 
+    @Override
     public PermissionGroupInfo getPermissionGroupInfo(String name, int flags) {
         // reader
         synchronized (mPackages) {
@@ -2193,6 +2202,7 @@
         }
     }
 
+    @Override
     public List<PermissionGroupInfo> getAllPermissionGroups(int flags) {
         // reader
         synchronized (mPackages) {
@@ -2278,6 +2288,7 @@
     }
 
 
+    @Override
     public void freeStorageAndNotify(final long freeStorageSize, final IPackageDataObserver observer) {
         mContext.enforceCallingOrSelfPermission(
                 android.Manifest.permission.CLEAR_APP_CACHE, null);
@@ -2303,6 +2314,7 @@
         });
     }
 
+    @Override
     public void freeStorage(final long freeStorageSize, final IntentSender pi) {
         mContext.enforceCallingOrSelfPermission(
                 android.Manifest.permission.CLEAR_APP_CACHE, null);
@@ -2424,6 +2436,7 @@
         return null;
     }
 
+    @Override
     public String[] getSystemSharedLibraryNames() {
         Set<String> libSet;
         synchronized (mPackages) {
@@ -2438,6 +2451,7 @@
         return null;
     }
 
+    @Override
     public FeatureInfo[] getSystemAvailableFeatures() {
         Collection<FeatureInfo> featSet;
         synchronized (mPackages) {
@@ -2456,6 +2470,7 @@
         return null;
     }
 
+    @Override
     public boolean hasSystemFeature(String name) {
         synchronized (mPackages) {
             return mAvailableFeatures.containsKey(name);
@@ -2470,6 +2485,7 @@
                 + " is not privileged to communicate with user=" + userId);
     }
 
+    @Override
     public int checkPermission(String permName, String pkgName) {
         synchronized (mPackages) {
             PackageParser.Package p = mPackages.get(pkgName);
@@ -2487,6 +2503,7 @@
         return PackageManager.PERMISSION_DENIED;
     }
 
+    @Override
     public int checkUidPermission(String permName, int uid) {
         synchronized (mPackages) {
             Object obj = mSettings.getUserIdLPr(UserHandle.getAppId(uid));
@@ -2661,18 +2678,21 @@
         return added;
     }
 
+    @Override
     public boolean addPermission(PermissionInfo info) {
         synchronized (mPackages) {
             return addPermissionLocked(info, false);
         }
     }
 
+    @Override
     public boolean addPermissionAsync(PermissionInfo info) {
         synchronized (mPackages) {
             return addPermissionLocked(info, true);
         }
     }
 
+    @Override
     public void removePermission(String name) {
         synchronized (mPackages) {
             checkPermissionTreeLP(name);
@@ -2717,6 +2737,7 @@
         }
     }
 
+    @Override
     public void grantPermission(String packageName, String permissionName) {
         mContext.enforceCallingOrSelfPermission(
                 android.Manifest.permission.GRANT_REVOKE_PERMISSIONS, null);
@@ -2746,6 +2767,7 @@
         }
     }
 
+    @Override
     public void revokePermission(String packageName, String permissionName) {
         int changedAppId = -1;
 
@@ -2804,12 +2826,14 @@
         }
     }
 
+    @Override
     public boolean isProtectedBroadcast(String actionName) {
         synchronized (mPackages) {
             return mProtectedBroadcasts.contains(actionName);
         }
     }
 
+    @Override
     public int checkSignatures(String pkg1, String pkg2) {
         synchronized (mPackages) {
             final PackageParser.Package p1 = mPackages.get(pkg1);
@@ -2822,6 +2846,7 @@
         }
     }
 
+    @Override
     public int checkUidSignatures(int uid1, int uid2) {
         // Map to base uids.
         uid1 = UserHandle.getAppId(uid1);
@@ -2961,6 +2986,7 @@
         return PackageManager.SIGNATURE_NO_MATCH;
     }
 
+    @Override
     public String[] getPackagesForUid(int uid) {
         uid = UserHandle.getAppId(uid);
         // reader
@@ -2984,6 +3010,7 @@
         return null;
     }
 
+    @Override
     public String getNameForUid(int uid) {
         // reader
         synchronized (mPackages) {
@@ -2999,6 +3026,7 @@
         return null;
     }
 
+    @Override
     public int getUidForSharedUser(String sharedUserName) {
         if(sharedUserName == null) {
             return -1;
@@ -3013,6 +3041,7 @@
         }
     }
 
+    @Override
     public int getFlagsForUid(int uid) {
         synchronized (mPackages) {
             Object obj = mSettings.getUserIdLPr(UserHandle.getAppId(uid));
@@ -3944,6 +3973,7 @@
         }
     }
 
+    @Override
     public List<ProviderInfo> queryContentProviders(String processName,
             int uid, int flags) {
         ArrayList<ProviderInfo> finalList = null;
@@ -3981,6 +4011,7 @@
         return finalList;
     }
 
+    @Override
     public InstrumentationInfo getInstrumentationInfo(ComponentName name,
             int flags) {
         // reader
@@ -3990,6 +4021,7 @@
         }
     }
 
+    @Override
     public List<InstrumentationInfo> queryInstrumentation(String targetPackage,
             int flags) {
         ArrayList<InstrumentationInfo> finalList =
@@ -4501,6 +4533,10 @@
     @Override
     public boolean performDexOpt(String packageName) {
         enforceSystemOrRoot("Only the system can request dexopt be performed");
+        return performDexOpt(packageName, true);
+    }
+
+    public boolean performDexOpt(String packageName, boolean updateUsage) {
 
         PackageParser.Package p;
         synchronized (mPackages) {
@@ -4508,7 +4544,9 @@
             if (p == null) {
                 return false;
             }
-            p.mLastPackageUsageTimeInMills = System.currentTimeMillis();
+            if (updateUsage) {
+                p.mLastPackageUsageTimeInMills = System.currentTimeMillis();
+            }
             mPackageUsage.write();
             if (!p.mDexOptNeeded) {
                 return false;
@@ -4521,6 +4559,25 @@
         }
     }
 
+    public HashSet<String> getPackagesThatNeedDexOpt() {
+        HashSet<String> pkgs = null;
+        synchronized (mPackages) {
+            for (PackageParser.Package p : mPackages.values()) {
+                if (DEBUG_DEXOPT) {
+                    Log.i(TAG, p.packageName + " mDexOptNeeded=" + p.mDexOptNeeded);
+                }
+                if (!p.mDexOptNeeded) {
+                    continue;
+                }
+                if (pkgs == null) {
+                    pkgs = new HashSet<String>();
+                }
+                pkgs.add(p.packageName);
+            }
+        }
+        return pkgs;
+    }
+
     public void shutdown() {
         mPackageUsage.write(true);
     }
@@ -7261,6 +7318,7 @@
         return mMediaMounted || Environment.isExternalStorageEmulated();
     }
 
+    @Override
     public PackageCleanItem nextPackageToClean(PackageCleanItem lastPackage) {
         // writer
         synchronized (mPackages) {
@@ -7446,6 +7504,7 @@
     }
 
     /* Called when a downloaded package installation has been confirmed by the user */
+    @Override
     public void installPackage(
             final Uri packageURI, final IPackageInstallObserver observer, final int flags,
             final String installerPackageName) {
@@ -7463,6 +7522,7 @@
                 installerPackageName, verificationParams, encryptionParams);
     }
 
+    @Override
     public void installPackageWithVerificationAndEncryption(Uri packageURI,
             IPackageInstallObserver observer, int flags, String installerPackageName,
             VerificationParams verificationParams, ContainerEncryptionParams encryptionParams) {
@@ -7872,6 +7932,7 @@
         }
     }
 
+    @Override
     public void finishPackageInstall(int token) {
         enforceSystemOrRoot("Only the system is allowed to finish installs");
 
@@ -7943,6 +8004,7 @@
                 -1);
     }
 
+    @Override
     public void setInstallerPackageName(String targetPackage, String installerPackageName) {
         final int uid = Binder.getCallingUid();
         // writer
@@ -10877,6 +10939,7 @@
         }
     }
 
+    @Override
     public void deleteApplicationCacheFiles(final String packageName,
             final IPackageDataObserver observer) {
         mContext.enforceCallingOrSelfPermission(
@@ -10929,6 +10992,7 @@
         return true;
     }
 
+    @Override
     public void getPackageSizeInfo(final String packageName, int userHandle,
             final IPackageStatsObserver observer) {
         mContext.enforceCallingOrSelfPermission(
@@ -11008,14 +11072,17 @@
     }
 
 
+    @Override
     public void addPackageToPreferred(String packageName) {
         Slog.w(TAG, "addPackageToPreferred: this is now a no-op");
     }
 
+    @Override
     public void removePackageFromPreferred(String packageName) {
         Slog.w(TAG, "removePackageFromPreferred: this is now a no-op");
     }
 
+    @Override
     public List<PackageInfo> getPreferredPackages(int flags) {
         return new ArrayList<PackageInfo>();
     }
@@ -11043,6 +11110,7 @@
         return Build.VERSION_CODES.CUR_DEVELOPMENT;
     }
 
+    @Override
     public void addPreferredActivity(IntentFilter filter, int match,
             ComponentName[] set, ComponentName activity, int userId) {
         addPreferredActivityInternal(filter, match, set, activity, true, userId);
@@ -11079,6 +11147,7 @@
         }
     }
 
+    @Override
     public void replacePreferredActivity(IntentFilter filter, int match,
             ComponentName[] set, ComponentName activity) {
         if (filter.countActions() != 1) {
@@ -11135,6 +11204,7 @@
         }
     }
 
+    @Override
     public void clearPackagePreferredActivities(String packageName) {
         final int uid = Binder.getCallingUid();
         // writer
@@ -11198,6 +11268,7 @@
         return changed;
     }
 
+    @Override
     public void resetPreferredActivities(int userId) {
         mContext.enforceCallingOrSelfPermission(
                 android.Manifest.permission.SET_PREFERRED_APPLICATIONS, null);
@@ -11211,6 +11282,7 @@
         }
     }
 
+    @Override
     public int getPreferredActivities(List<IntentFilter> outFilters,
             List<ComponentName> outActivities, String packageName) {
 
@@ -11518,6 +11590,7 @@
                 new int[] {UserHandle.getUserId(packageUid)});
     }
 
+    @Override
     public void setPackageStoppedState(String packageName, boolean stopped, int userId) {
         if (!sUserManager.exists(userId)) return;
         final int uid = Binder.getCallingUid();
@@ -11534,6 +11607,7 @@
         }
     }
 
+    @Override
     public String getInstallerPackageName(String packageName) {
         // reader
         synchronized (mPackages) {
@@ -11563,6 +11637,7 @@
         }
     }
 
+    @Override
     public void enterSafeMode() {
         enforceSystemOrRoot("Only the system can request entering safe mode");
 
@@ -11571,6 +11646,7 @@
         }
     }
 
+    @Override
     public void systemReady() {
         mSystemReady = true;
 
@@ -11616,10 +11692,12 @@
         sUserManager.systemReady();
     }
 
+    @Override
     public boolean isSafeMode() {
         return mSafeMode;
     }
 
+    @Override
     public boolean hasSystemUidErrors() {
         return mHasSystemUidErrors;
     }
@@ -12117,6 +12195,7 @@
     /*
      * Update media status on PackageManager.
      */
+    @Override
     public void updateExternalMediaStatus(final boolean mediaStatus, final boolean reportStatus) {
         int callingUid = Binder.getCallingUid();
         if (callingUid != 0 && callingUid != Process.SYSTEM_UID) {
@@ -12711,6 +12790,7 @@
         });
     }
 
+    @Override
     public boolean setInstallLocation(int loc) {
         mContext.enforceCallingOrSelfPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS,
                 null);
@@ -12726,6 +12806,7 @@
         return false;
    }
 
+    @Override
     public int getInstallLocation() {
         return android.provider.Settings.Global.getInt(mContext.getContentResolver(),
                 android.provider.Settings.Global.DEFAULT_INSTALL_LOCATION,
diff --git a/services/java/com/android/server/SystemServer.java b/services/java/com/android/server/SystemServer.java
index 7c9f7a8..722b797 100644
--- a/services/java/com/android/server/SystemServer.java
+++ b/services/java/com/android/server/SystemServer.java
@@ -73,6 +73,7 @@
 import com.android.server.net.NetworkStatsService;
 import com.android.server.notification.NotificationManagerService;
 import com.android.server.os.SchedulingPolicyService;
+import com.android.server.pm.BackgroundDexOptService;
 import com.android.server.pm.Installer;
 import com.android.server.pm.LauncherAppsService;
 import com.android.server.pm.PackageManagerService;
@@ -962,6 +963,13 @@
                 } catch (Throwable e) {
                     Slog.e(TAG, "Failure starting TrustManagerService", e);
                 }
+
+                try {
+                    Slog.i(TAG, "BackgroundDexOptService");
+                    new BackgroundDexOptService(context);
+                } catch (Throwable e) {
+                    reportWtf("starting BackgroundDexOptService", e);
+                }
             }
 
             try {