Scrims should be grey when in-app

Bug: 38164389
Test: runtest -x colorextraction/tests/src/com/google/android/colorextraction/ColorExtractorTest.java
Test: runtest -x tests/src/com/android/systemui/colorextraction/SysuiColorExtractorTests.java
Change-Id: Ifcc04a8562e46b4f65bce0470ccd6c02dffcf377
diff --git a/services/core/java/com/android/server/wm/WallpaperVisibilityListeners.java b/services/core/java/com/android/server/wm/WallpaperVisibilityListeners.java
new file mode 100644
index 0000000..2c06851
--- /dev/null
+++ b/services/core/java/com/android/server/wm/WallpaperVisibilityListeners.java
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2017 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.wm;
+
+import android.os.RemoteCallbackList;
+import android.os.RemoteException;
+import android.util.SparseArray;
+import android.view.IWallpaperVisibilityListener;
+
+/**
+ * Manages and trigger wallpaper visibility listeners.
+ */
+class WallpaperVisibilityListeners {
+
+    /**
+     * A map of displayIds and its listeners.
+     */
+    private final SparseArray<RemoteCallbackList<IWallpaperVisibilityListener>> mDisplayListeners =
+            new SparseArray<>();
+
+    void registerWallpaperVisibilityListener(IWallpaperVisibilityListener listener,
+            int displayId) {
+        RemoteCallbackList<IWallpaperVisibilityListener> listeners =
+                mDisplayListeners.get(displayId);
+        if (listeners == null) {
+            listeners = new RemoteCallbackList<>();
+            mDisplayListeners.append(displayId, listeners);
+        }
+        listeners.register(listener);
+    }
+
+    void unregisterWallpaperVisibilityListener(IWallpaperVisibilityListener listener,
+            int displayId) {
+        RemoteCallbackList<IWallpaperVisibilityListener> listeners =
+                mDisplayListeners.get(displayId);
+        if (listeners == null) {
+            return;
+        }
+        listeners.unregister(listener);
+    }
+
+    void notifyWallpaperVisibilityChanged(DisplayContent displayContent) {
+        final int displayId = displayContent.getDisplayId();
+        final boolean visible = displayContent.mWallpaperController.isWallpaperVisible();
+        RemoteCallbackList<IWallpaperVisibilityListener> displayListeners =
+                mDisplayListeners.get(displayId);
+
+        // No listeners for this display.
+        if (displayListeners == null) {
+            return;
+        }
+
+        int i = displayListeners.beginBroadcast();
+        while (i > 0) {
+            i--;
+            IWallpaperVisibilityListener listener = displayListeners.getBroadcastItem(i);
+            try {
+                listener.onWallpaperVisibilityChanged(visible, displayId);
+            } catch (RemoteException e) {
+                // Nothing to do in here, RemoteCallbackListener will clean it up.
+            }
+        }
+        displayListeners.finishBroadcast();
+    }
+}