Adds volume level measurements to the AudioInputController for low-latency clients

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 3facfb511d18670a4a6d2ce0e0f19071099fe0e8..981de1d0c5b09ad45de5246fd9764f0bb020b1de 100644
--- a/media/audio/audio_input_controller.h
+++ b/media/audio/audio_input_controller.h
@@ -16,6 +16,9 @@
 #include "base/timer/timer.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_manager_base.h"
+#include "media/audio/audio_parameters.h"
+#include "media/audio/audio_power_monitor.h"
+#include "media/base/audio_bus.h"
 
 // An AudioInputController controls an AudioInputStream and records data
 // from this input stream. The two main methods are Record() and Close() and
@@ -72,6 +75,11 @@
 //
 namespace media {
 
+// Only do power monitoring for non-mobile platforms to save resources.
+#if !defined(OS_ANDROID) && !defined(OS_IOS)
+#define AUDIO_POWER_MONITORING
+#endif
+
 class UserInputMonitor;
 
 class MEDIA_EXPORT AudioInputController
@@ -111,6 +119,8 @@ class MEDIA_EXPORT AudioInputController
                          ErrorCode error_code) = 0;
     virtual void OnData(AudioInputController* controller, const uint8* data,
                         uint32 size) = 0;
+    virtual void OnLog(AudioInputController* controller,
+                       const std::string& message) = 0;
 
    protected:
     virtual ~EventHandler() {}
@@ -252,6 +262,7 @@ class MEDIA_EXPORT AudioInputController
   void DoSetVolume(double volume);
   void DoSetAutomaticGainControl(bool enabled);
   void DoOnData(scoped_ptr<uint8[]> data, uint32 size);
+  void DoLogAudioLevel();
 
   // Method to check if we get recorded data after a stream was started,
   // and log the result to UMA.
@@ -309,6 +320,16 @@ class MEDIA_EXPORT AudioInputController
 
   UserInputMonitor* user_input_monitor_;
 
+#if defined(AUDIO_POWER_MONITORING)

[no longer working on chromium, 2014/05/26 14:20:16]

I don't think you save much by excluding these members from those platfroms, I
suggest removing the AUDIO_POWER_MONITORING here and move the definition of
AUDIO_POWER_MONITORING to the implementation instead

[henrika (OOO until Aug 14), 2014/05/26 15:01:17]

I copied how it was done on the output side (in the AOC) to make it symmetric.
OK?

[henrika (OOO until Aug 14), 2014/05/27 07:46:36]

In addition, we should really do our best to simplify as much as possible for
mobile. Every byte counts.

+  // Scans audio samples from OnData() as input to compute audio levels.
+  scoped_ptr<AudioPowerMonitor> audio_level_;
+
+  // We need these to be able to feed data to the AudioPowerMonitor.
+  scoped_ptr<AudioBus> audio_bus_;
+  media::AudioParameters audio_params_;
+  base::TimeTicks last_audio_level_log_time_;
+#endif
+
   size_t prev_key_down_count_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioInputController);