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..5b29ac8acf05daf17f78e7030fd205d4837bd643 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
@@ -309,6 +317,16 @@ class MEDIA_EXPORT AudioInputController
 
   UserInputMonitor* user_input_monitor_;
 
+#if defined(AUDIO_POWER_MONITORING)
+  // 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);