Migrate AudioFocusChangeListener to browser and always send GAIN

content/public/android/java/src/org/chromium/content/browser/AudioFocusManager.java

Index: content/public/android/java/src/org/chromium/content/browser/AudioFocusManager.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/AudioFocusManager.java b/content/public/android/java/src/org/chromium/content/browser/AudioFocusManager.java
new file mode 100644
index 0000000000000000000000000000000000000000..9b8e7045745c4b70d0bafc391961857c90a3658f
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content/browser/AudioFocusManager.java
@@ -0,0 +1,99 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.content.browser;
+
+import android.content.Context;
+import android.media.AudioManager;
+import android.media.AudioManager.OnAudioFocusChangeListener;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+import org.chromium.base.Log;
+
+import java.util.AbstractMap.SimpleEntry;
+import java.util.HashSet;
+import java.util.Map.Entry;
+import java.util.Set;
+
+@JNINamespace("content")
+class AudioFocusManager implements OnAudioFocusChangeListener {
+    private static final String TAG = "AudioFocusManager";
+
+    private static AudioFocusManager sInstance;
+
+    private final Context mContext;
+
+    // Maintain a set of native pointer and player ID pairs.
+    private final Set<Entry<Long, Integer>> mPlayers =
+            new HashSet<Entry<Long, Integer>>();
+
+    private AudioFocusManager(Context context) {
+        mContext = context;
+    }
+
+    @CalledByNative
+    public static AudioFocusManager getInstance(Context context) {
+        if (sInstance == null) {
+            sInstance = new AudioFocusManager(context.getApplicationContext());
+        }
+        return sInstance;
+    }
+
+    @Override
+    public void onAudioFocusChange(int focusChange) {
+        if (focusChange == AudioManager.AUDIOFOCUS_LOSS
+                || focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT
+                || focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK) {
+            interruptAllPlayers();
+            mPlayers.clear();
+
+            AudioManager audioManager = (AudioManager) mContext.getSystemService(
+                    Context.AUDIO_SERVICE);
+            audioManager.abandonAudioFocus(this);
+        }
+    }
+
+    @CalledByNative
+    private void abandonAudioFocus(long nativeAudioFocusManager, int playerId) {
+        Entry<Long, Integer> player =
+                new SimpleEntry<Long, Integer>(nativeAudioFocusManager, playerId);
+
+        if (mPlayers.remove(player) && mPlayers.isEmpty()) {
+            AudioManager audioManager = (AudioManager) mContext.getSystemService(
+                    Context.AUDIO_SERVICE);
+            audioManager.abandonAudioFocus(this);
+        }
+    }
+
+    @CalledByNative
+    private void requestAudioFocus(long nativeAudioFocusManager, int playerId) {
+        AudioManager audioManager = (AudioManager) mContext.getSystemService(
+                Context.AUDIO_SERVICE);
+        int result = audioManager.requestAudioFocus(
+                this,
+                AudioManager.STREAM_MUSIC,
+                AudioManager.AUDIOFOCUS_GAIN);
+
+        if (result == AudioManager.AUDIOFOCUS_REQUEST_FAILED) {
+            Log.w(TAG, "requestAudioFocus: Request for audio focus failed");
+            nativeOnMediaInterrupted(nativeAudioFocusManager, playerId);
+            return;
+        }
+
+        Entry<Long, Integer> player =
+                new SimpleEntry<Long, Integer>(nativeAudioFocusManager, playerId);
+        mPlayers.add(player);
+    }
+
+    private void interruptAllPlayers() {
+        for (Entry<Long, Integer> player : mPlayers) {
+            long nativeAudioFocusManager = player.getKey();
+            int playerId = player.getValue();
+            nativeOnMediaInterrupted(nativeAudioFocusManager, playerId);
+        }
+    }
+
+    private native void nativeOnMediaInterrupted(long nativeAudioFocusManager, int playerId);
+}