Add way to set volume on all output audio streams on Android.

This is to support controlling volume level of Web Audio for
cast_shell on Android.

BUG=460303

Review URL: https://codereview.chromium.org/943723004

Cr-Commit-Position: refs/heads/master@{#317806}

3 files changed, 46 insertions, 1 deletions

diff --git a/media/audio/android/audio_manager_android.cc b/media/audio/android/audio_manager_android.cc
index 7f229e0..0590ffc 100644
--- a/media/audio/android/audio_manager_android.cc
+++ b/media/audio/android/audio_manager_android.cc
@@ -48,7 +48,9 @@ AudioManager* CreateAudioManager(AudioLogFactory* audio_log_factory) {
 
 AudioManagerAndroid::AudioManagerAndroid(AudioLogFactory* audio_log_factory)
     : AudioManagerBase(audio_log_factory),
-      communication_mode_is_on_(false) {
+      communication_mode_is_on_(false),
+      output_volume_override_set_(false),
+      output_volume_override_(0) {
   SetMaxOutputStreamsAllowed(kMaxOutputStreams);
 
   // WARNING: This is executed on the UI loop, do not add any code here which
@@ -265,6 +267,22 @@ void AudioManagerAndroid::SetMute(JNIEnv* env, jobject obj, jboolean muted) {
           muted));
 }
 
+void AudioManagerAndroid::SetOutputVolumeOverride(double volume) {
+  GetTaskRunner()->PostTask(
+      FROM_HERE,
+      base::Bind(
+          &AudioManagerAndroid::DoSetVolumeOnAudioThread,
+          base::Unretained(this),
+          volume));
+}
+
+bool AudioManagerAndroid::HasOutputVolumeOverride(double* out_volume) const {
+  if (output_volume_override_set_) {
+    *out_volume = output_volume_override_;
+  }
+  return output_volume_override_set_;
+}
+
 AudioParameters AudioManagerAndroid::GetPreferredOutputStreamParameters(
     const std::string& output_device_id,
     const AudioParameters& input_params) {
@@ -382,4 +400,15 @@ void AudioManagerAndroid::DoSetMuteOnAudioThread(bool muted) {
   }
 }
 
+void AudioManagerAndroid::DoSetVolumeOnAudioThread(double volume) {
+  output_volume_override_set_ = true;
+  output_volume_override_ = volume;
+
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  for (OutputStreams::iterator it = streams_.begin();
+       it != streams_.end(); ++it) {
+    (*it)->SetVolume(volume);
+  }
+}
+
 }  // namespace media
diff --git a/media/audio/android/audio_manager_android.h b/media/audio/android/audio_manager_android.h
index 496b8cb..c64e6ee 100644
--- a/media/audio/android/audio_manager_android.h
+++ b/media/audio/android/audio_manager_android.h
@@ -55,6 +55,11 @@ class MEDIA_EXPORT AudioManagerAndroid : public AudioManagerBase {
 
   void SetMute(JNIEnv* env, jobject obj, jboolean muted);
 
+  // Sets a volume that applies to all this manager's output audio streams.
+  // This overrides other SetVolume calls (e.g. through AudioHostMsg_SetVolume).
+  void SetOutputVolumeOverride(double volume);
+  bool HasOutputVolumeOverride(double* out_volume) const;
+
  protected:
   ~AudioManagerAndroid() override;
 
@@ -75,6 +80,7 @@ class MEDIA_EXPORT AudioManagerAndroid : public AudioManagerBase {
   int GetOptimalOutputFrameSize(int sample_rate, int channels);
 
   void DoSetMuteOnAudioThread(bool muted);
+  void DoSetVolumeOnAudioThread(double volume);
 
   // Java AudioManager instance.
   base::android::ScopedJavaGlobalRef<jobject> j_audio_manager_;
@@ -86,6 +92,10 @@ class MEDIA_EXPORT AudioManagerAndroid : public AudioManagerBase {
   // input stream is destroyed. Also affects the stream type of output streams.
   bool communication_mode_is_on_;
 
+  // If set, overrides volume level on output streams
+  bool output_volume_override_set_;
+  double output_volume_override_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioManagerAndroid);
 };
 
diff --git a/media/audio/android/opensles_output.cc b/media/audio/android/opensles_output.cc
index c044204..2974e14 100644
--- a/media/audio/android/opensles_output.cc
+++ b/media/audio/android/opensles_output.cc
@@ -165,6 +165,12 @@ void OpenSLESOutputStream::Close() {
 void OpenSLESOutputStream::SetVolume(double volume) {
   DVLOG(2) << "OpenSLESOutputStream::SetVolume(" << volume << ")";
   DCHECK(thread_checker_.CalledOnValidThread());
+
+  double volume_override = 0;
+  if (audio_manager_->HasOutputVolumeOverride(&volume_override)) {
+    volume = volume_override;
+  }
+
   float volume_float = static_cast<float>(volume);
   if (volume_float < 0.0f || volume_float > 1.0f) {
     return;