Mute audio when volume is zero on Android.

media/audio/android/audio_manager_android.cc

Index: media/audio/android/audio_manager_android.cc
diff --git a/media/audio/android/audio_manager_android.cc b/media/audio/android/audio_manager_android.cc
index 34665103b2856c9ac7917a86f136c9c221189693..868a58044344036d51fabd7ba4923d601a3c41a0 100644
--- a/media/audio/android/audio_manager_android.cc
+++ b/media/audio/android/audio_manager_android.cc
@@ -52,7 +52,8 @@ AudioManagerAndroid::AudioManagerAndroid() {
   j_audio_manager_.Reset(
       Java_AudioManagerAndroid_createAudioManagerAndroid(
           base::android::AttachCurrentThread(),
-          base::android::GetApplicationContext()));
+          base::android::GetApplicationContext(),
+          reinterpret_cast<intptr_t>(this)));
   Init();
 }
 
@@ -125,6 +126,12 @@ AudioOutputStream* AudioManagerAndroid::MakeAudioOutputStream(
   if (stream && output_stream_count() == 1) {
     SetAudioMode(kAudioModeInCommunication);
   }
+
+  {
+    base::AutoLock lock(streams_lock_);
+    streams_.insert(static_cast<OpenSLESOutputStream*>(stream));
+  }
+
   return stream;
 }
 
@@ -140,6 +147,8 @@ void AudioManagerAndroid::ReleaseOutputStream(AudioOutputStream* stream) {
   if (!output_stream_count()) {
     SetAudioMode(kAudioModeNormal);
   }
+  base::AutoLock lock(streams_lock_);
+  streams_.erase(static_cast<OpenSLESOutputStream*>(stream));
 }
 
 void AudioManagerAndroid::ReleaseInputStream(AudioInputStream* stream) {
@@ -237,6 +246,23 @@ void AudioManagerAndroid::Close() {
       j_audio_manager_.obj());
 }
 
+void AudioManagerAndroid::SetMute(JNIEnv* env, jobject obj, jboolean muted) {
+  GetMessageLoop()->PostTask(
+      FROM_HERE,
+      base::Bind(
+          &AudioManagerAndroid::DoSetMuteOnAudioThread,
+          base::Unretained(this),
+          muted));
+}
+
+void AudioManagerAndroid::DoSetMuteOnAudioThread(bool muted) {
+  base::AutoLock lock(streams_lock_);
+  for (OutputStreams::iterator it = streams_.begin();
+       it != streams_.end(); ++it) {
+    (*it)->SetMute(muted);
+  }
+}
+
 void AudioManagerAndroid::SetAudioMode(int mode) {
   Java_AudioManagerAndroid_setMode(
       base::android::AttachCurrentThread(),