Use AudioStreamMonitor to control power save blocking.

media/audio/audio_output_controller.cc

Index: media/audio/audio_output_controller.cc
diff --git a/media/audio/audio_output_controller.cc b/media/audio/audio_output_controller.cc
index fb01254568adebb5b56baa9cb421dcc0940716ca..45d308db3effd64f12394570200c1f90b515ea4f 100644
--- a/media/audio/audio_output_controller.cc
+++ b/media/audio/audio_output_controller.cc
@@ -17,12 +17,6 @@ using base::TimeDelta;
 
 namespace media {
 
-#if defined(AUDIO_POWER_MONITORING)
-// Time constant for AudioPowerMonitor.  See AudioPowerMonitor ctor comments for
-// semantics.  This value was arbitrarily chosen, but seems to work well.
-static const int kPowerMeasurementTimeConstantMillis = 10;
-#endif
-
 AudioOutputController::AudioOutputController(
     AudioManager* audio_manager,
     EventHandler* handler,
@@ -39,11 +33,9 @@ AudioOutputController::AudioOutputController(
       state_(kEmpty),
       sync_reader_(sync_reader),
       message_loop_(audio_manager->GetTaskRunner()),
-#if defined(AUDIO_POWER_MONITORING)
       power_monitor_(
           params.sample_rate(),
           TimeDelta::FromMilliseconds(kPowerMeasurementTimeConstantMillis)),
-#endif
       on_more_io_data_called_(0) {
   DCHECK(audio_manager);
   DCHECK(handler_);
@@ -200,11 +192,9 @@ void AudioOutputController::StopStream() {
     wedge_timer_.reset();
     stream_->Stop();
 
-#if defined(AUDIO_POWER_MONITORING)
     // A stopped stream is silent, and power_montior_.Scan() is no longer being
     // called; so we must reset the power monitor.
     power_monitor_.Reset();
-#endif
 
     state_ = kPaused;
   }
@@ -306,9 +296,8 @@ int AudioOutputController::OnMoreData(AudioBus* dest,
   sync_reader_->UpdatePendingBytes(
       buffers_state.total_bytes() + frames * params_.GetBytesPerFrame());
 
-#if defined(AUDIO_POWER_MONITORING)
-  power_monitor_.Scan(*dest, frames);
-#endif
+  if (will_monitor_audio_levels())
+    power_monitor_.Scan(*dest, frames);
 
   return frames;
 }
@@ -412,12 +401,8 @@ void AudioOutputController::DoStopDiverting() {
 }
 
 std::pair<float, bool> AudioOutputController::ReadCurrentPowerAndClip() {
-#if defined(AUDIO_POWER_MONITORING)
+  DCHECK(will_monitor_audio_levels());
   return power_monitor_.ReadCurrentPowerAndClip();
-#else
-  NOTREACHED();
-  return std::make_pair(AudioPowerMonitor::zero_power(), false);
-#endif
 }
 
 void AudioOutputController::WedgeCheck() {