Mute audio when volume is zero on Android.

media/base/android/java/src/org/chromium/media/AudioManagerAndroid.java

Index: media/base/android/java/src/org/chromium/media/AudioManagerAndroid.java
diff --git a/media/base/android/java/src/org/chromium/media/AudioManagerAndroid.java b/media/base/android/java/src/org/chromium/media/AudioManagerAndroid.java
index db674f52d3b9f2a0a43978447f7078cdb5ef1671..93171a76975b7398ecef3e276e5b0eba9f98b5ca 100644
--- a/media/base/android/java/src/org/chromium/media/AudioManagerAndroid.java
+++ b/media/base/android/java/src/org/chromium/media/AudioManagerAndroid.java
@@ -7,16 +7,23 @@ package org.chromium.media;
 import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.BluetoothManager;
 import android.content.BroadcastReceiver;
+import android.content.ContentResolver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.pm.PackageManager;
+import android.database.ContentObserver;
 import android.media.AudioFormat;
 import android.media.AudioManager;
 import android.media.AudioRecord;
 import android.media.AudioTrack;
+import android.net.Uri;
 import android.os.Build;
+import android.os.Handler;
+import android.os.Looper;
 import android.os.Process;
+import android.provider.Settings;
+import android.provider.Settings.System;
 import android.util.Log;
 
 import java.util.Arrays;
@@ -106,6 +113,7 @@ class AudioManagerAndroid {
 
     private final AudioManager mAudioManager;
     private final Context mContext;
+    private final long mNativeAudioManagerAndroid;
 
     private boolean mHasBluetoothPermission = false;
     private boolean mIsInitialized = false;
@@ -117,18 +125,28 @@ class AudioManagerAndroid {
     // Contains a list of currently available audio devices.
     private boolean[] mAudioDevices = new boolean[DEVICE_COUNT];
 
+    private final ContentResolver mContentResolver;
+    private SettingsObserver mSettingsObserver = null;
+    private SettingsObserverThread mSettingsObserverThread = null;
+    private int mCurrentVolume;
+    private final Object mSettingsObserverLock = new Object();
+
     // Broadcast receiver for wired headset intent broadcasts.
     private BroadcastReceiver mWiredHeadsetReceiver;
 
     /** Construction */
     @CalledByNative
-    private static AudioManagerAndroid createAudioManagerAndroid(Context context) {
-        return new AudioManagerAndroid(context);
+    private static AudioManagerAndroid createAudioManagerAndroid(
+            Context context,
+            long nativeAudioManagerAndroid) {
+        return new AudioManagerAndroid(context, nativeAudioManagerAndroid);
     }
 
-    private AudioManagerAndroid(Context context) {
+    private AudioManagerAndroid(Context context, long nativeAudioManagerAndroid) {
         mContext = context;
+        mNativeAudioManagerAndroid = nativeAudioManagerAndroid;
         mAudioManager = (AudioManager)mContext.getSystemService(Context.AUDIO_SERVICE);
+        mContentResolver = mContext.getContentResolver();
     }
 
     /**
@@ -174,6 +192,16 @@ class AudioManagerAndroid {
         initBluetooth();
 
         mIsInitialized = true;
+
+        mSettingsObserverThread = new SettingsObserverThread();
+        mSettingsObserverThread.start();
+        synchronized(mSettingsObserverLock) {
+            try {
+                mSettingsObserverLock.wait();
+            } catch (InterruptedException e) {
+                Log.e(TAG, "unregisterHeadsetReceiver exception: " + e.getMessage());
+            }
+        }
     }
 
     /**
@@ -185,6 +213,14 @@ class AudioManagerAndroid {
         if (!mIsInitialized)
             return;
 
+        if (mSettingsObserverThread != null ) {
+            mSettingsObserverThread = null;
+        }
+        if (mSettingsObserver != null) {
+            mContentResolver.unregisterContentObserver(mSettingsObserver);
+            mSettingsObserver = null;
+        }
+
         unregisterForWiredHeadsetIntentBroadcast();
 
         // Restore previously stored audio states.
@@ -553,4 +589,40 @@ class AudioManagerAndroid {
     private void loge(String msg) {
         Log.e(TAG, msg);
     }
+
+    private class SettingsObserver extends ContentObserver {
+        SettingsObserver() {
+            super(new Handler());
+            mContentResolver.registerContentObserver(Settings.System.CONTENT_URI, true, this);
+        }
+
+        @Override
+        public void onChange(boolean selfChange) {
+            super.onChange(selfChange);
+            int volume = mAudioManager.getStreamVolume(AudioManager.STREAM_VOICE_CALL);
+            nativeSetMute(mNativeAudioManagerAndroid, (volume == 0));
+        }
+    }
+
+    private native void nativeSetMute(long nativeAudioManagerAndroid, boolean muted);
+
+    private class SettingsObserverThread extends Thread {
+        SettingsObserverThread() {
+            super("SettinsObserver");
+        }
+
+        @Override
+        public void run() {
+            // Set this thread up so the handler will work on it.
+            Looper.prepare();
+
+            synchronized(mSettingsObserverLock) {
+                mSettingsObserver = new SettingsObserver();
+                mSettingsObserverLock.notify();
+            }
+
+            // Listen for volume change.
+            Looper.loop();
+        }
+    }
 }