Mute audio when volume is zero on Android.

media/audio/android/audio_manager_android.cc

 // Copyright (c) 2012 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.
 
 #include "media/audio/android/audio_manager_android.h"
 
 #include "base/logging.h"
 #include "jni/AudioManagerAndroid_jni.h"
 #include "media/audio/android/opensles_input.h"
 #include "media/audio/android/opensles_output.h"
@@ skipping 23 matching lines @@
 AudioManager* CreateAudioManager() {
   return new AudioManagerAndroid();
 }
 
 AudioManagerAndroid::AudioManagerAndroid() {
   SetMaxOutputStreamsAllowed(kMaxOutputStreams);
 
   j_audio_manager_.Reset(
       Java_AudioManagerAndroid_createAudioManagerAndroid(
           base::android::AttachCurrentThread(),
-          base::android::GetApplicationContext()));
+          base::android::GetApplicationContext(),
+          reinterpret_cast<intptr_t>(this)));
 }
 
 AudioManagerAndroid::~AudioManagerAndroid() {
   Shutdown();
 }
 
 bool AudioManagerAndroid::HasAudioOutputDevices() {
   return true;
 }
 
@@ skipping 20 matching lines @@
   int buffer_size = Java_AudioManagerAndroid_getMinInputFrameSize(
       base::android::AttachCurrentThread(), GetNativeOutputSampleRate(),
       ChannelLayoutToChannelCount(channel_layout));
 
   return AudioParameters(
       AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout,
       GetNativeOutputSampleRate(), 16,
       buffer_size <= 0 ? kDefaultInputBufferSize : buffer_size);
 }
 
 AudioOutputStream* AudioManagerAndroid::MakeAudioOutputStream(

[tommi (sloooow) - chröme, 2013/12/02 18:36:00]

Can we DCHECK that all methods that touch streams_ are running on the audio
thread?

[wjia(left Chromium), 2013/12/02 21:49:49]

Not now. Please refer to comments in AudioManagerBase::MakeAudioOutputStream
(https://code.google.com/p/chromium/codesearch#chromium/src/media/audio/audio_...).

[tommi (sloooow) - chröme, 2013/12/03 08:56:24]

Ju On 2013/12/02 21:49:49, wjia wrote:
Ah. OK in that case you need to post a task to the audio thread for inserting
into streams_ or use a lock to protect it. 

[wjia(left Chromium), 2013/12/04 00:53:29]

Done.

     const AudioParameters& params,
     const std::string& device_id,
     const std::string& input_device_id) {
   AudioOutputStream* stream =
       AudioManagerBase::MakeAudioOutputStream(params, std::string(),
           std::string());
   if (stream && output_stream_count() == 1) {
     SetAudioMode(kAudioModeInCommunication);
     RegisterHeadsetReceiver();
   }
+  streams_.insert(reinterpret_cast<OpenSLESOutputStream*>(stream));

[tommi (sloooow) - chröme, 2013/12/02 18:36:00]

static_cast

[wjia(left Chromium), 2013/12/02 21:49:49]

Done.

   return stream;
 }
 
 AudioInputStream* AudioManagerAndroid::MakeAudioInputStream(
     const AudioParameters& params, const std::string& device_id) {
   AudioInputStream* stream =
       AudioManagerBase::MakeAudioInputStream(params, device_id);
   return stream;
 }
 
 void AudioManagerAndroid::ReleaseOutputStream(AudioOutputStream* stream) {
   AudioManagerBase::ReleaseOutputStream(stream);
   if (!output_stream_count()) {
     UnregisterHeadsetReceiver();
     SetAudioMode(kAudioModeNormal);
   }
+  streams_.erase(reinterpret_cast<OpenSLESOutputStream*>(stream));

[tommi (sloooow) - chröme, 2013/12/02 18:36:00]

static_cast

[wjia(left Chromium), 2013/12/02 21:49:49]

Done.

[tommi (sloooow) - chröme, 2013/12/03 08:56:24]

Looks like there's a race here too. 

[wjia(left Chromium), 2013/12/04 00:53:29]

Done.

 }
 
 void AudioManagerAndroid::ReleaseInputStream(AudioInputStream* stream) {
   AudioManagerBase::ReleaseInputStream(stream);
 }
 
 AudioOutputStream* AudioManagerAndroid::MakeLinearOutputStream(
     const AudioParameters& params) {
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LINEAR, params.format());
   return new OpenSLESOutputStream(this, params);
@@ skipping 59 matching lines @@
   return AudioParameters(
       AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout, input_channels,
       sample_rate, bits_per_sample, buffer_size);
 }
 
 // static
 bool AudioManagerAndroid::RegisterAudioManager(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
+void AudioManagerAndroid::SetMute(JNIEnv* env, jobject obj, jboolean state) {
+  message_loop_->PostTask(
+      FROM_HERE,
+      base::Bind(
+          &AudioManagerAndroid::DoSetMuteOnAudioThread,
+          base::Unretained(this),
+          state));
+}
+
+void AudioManagerAndroid::DoSetMuteOnAudioThread(bool state) {
+  for (OutputStreams::iterator it=streams_.begin();

[tommi (sloooow) - chröme, 2013/12/02 18:36:00]

spaces around =

[wjia(left Chromium), 2013/12/02 21:49:49]

Done.

+       it != streams_.end(); ++it) {
+    (*it)->SetMute(state);
+  }
+}
+
 void AudioManagerAndroid::SetAudioMode(int mode) {
   Java_AudioManagerAndroid_setMode(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj(), mode);
 }
 
 void AudioManagerAndroid::RegisterHeadsetReceiver() {
   Java_AudioManagerAndroid_registerHeadsetReceiver(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
@@ skipping 17 matching lines @@
       j_audio_manager_.obj());
 }
 
 int AudioManagerAndroid::GetAudioLowLatencyOutputFrameSize() {
   return Java_AudioManagerAndroid_getAudioLowLatencyOutputFrameSize(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
 
 }  // namespace media