Only log audio input silence state UMA stats for low latency mode and if not fake device.

media/audio/audio_input_controller.h

Index: media/audio/audio_input_controller.h
diff --git a/media/audio/audio_input_controller.h b/media/audio/audio_input_controller.h
index e1e14ee3c30e94b07ed34f0043e215b635a94168..7be4796ddafee83c0e47291f494d2f7c4b85efe9 100644
--- a/media/audio/audio_input_controller.h
+++ b/media/audio/audio_input_controller.h
@@ -251,6 +251,12 @@ class MEDIA_EXPORT AudioInputController
   // Elements in this enum should not be deleted or rearranged; the only
   // permitted operation is to add new elements before SILENCE_STATE_MAX and
   // update SILENCE_STATE_MAX.
+  // Possible silence state transitions:
+  //           SILENCE_STATE_AUDIO_AND_SILENCE
+  //               ^                  ^
+  // SILENCE_STATE_ONLY_AUDIO   SILENCE_STATE_ONLY_SILENCE
+  //               ^                  ^
+  //            SILENCE_STATE_NO_MEASUREMENT
   enum SilenceState {
     SILENCE_STATE_NO_MEASUREMENT = 0,
     SILENCE_STATE_ONLY_AUDIO = 1,
@@ -268,6 +274,9 @@ class MEDIA_EXPORT AudioInputController
   // Methods called on the audio thread (owned by the AudioManager).
   void DoCreate(AudioManager* audio_manager, const AudioParameters& params,
                 const std::string& device_id);
+  void DoCreateForLowLatency(AudioManager* audio_manager,

[no longer working on chromium, 2014/08/21 09:11:56]

Please see comments above, I don't think you need DoCreateForLowLatency().

[Henrik Grunell, 2014/08/21 11:06:10]

See comment above.

+                             const AudioParameters& params,
+                             const std::string& device_id);
   void DoCreateForStream(AudioInputStream* stream_to_control);
   void DoRecord();
   void DoClose();
@@ -292,6 +301,11 @@ class MEDIA_EXPORT AudioInputController
   bool GetDataIsActive();
 
 #if defined(AUDIO_POWER_MONITORING)
+  // Updates the silence state, see enum SilenceState above for state
+  // transitions.
+  void UpdateSilenceState(bool silence);
+
+  // Logs the silence state as UMA stat.
   void LogSilenceState(SilenceState value);
 #endif
 
@@ -345,6 +359,9 @@ class MEDIA_EXPORT AudioInputController
   media::AudioParameters audio_params_;
   base::TimeTicks last_audio_level_log_time_;
 
+  // Whether the silence state should sent as UMA stat.
+  bool log_silence_state_;
+
   // The silence report sent as UMA stat at the end of a session.
   SilenceState silence_state_;
 #endif