Replace AudioSilenceDetector with an AudioPowerMonitor.

content/browser/renderer_host/media/audio_renderer_host.cc

Index: content/browser/renderer_host/media/audio_renderer_host.cc
diff --git a/content/browser/renderer_host/media/audio_renderer_host.cc b/content/browser/renderer_host/media/audio_renderer_host.cc
index 0c8c310350bcfb86116470fc0889e092fdbd6d3e..c6ff85a176b1765ea819cce20690dd02df642028 100644
--- a/content/browser/renderer_host/media/audio_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_renderer_host.cc
@@ -4,6 +4,8 @@
 
 #include "content/browser/renderer_host/media/audio_renderer_host.h"
 
+#include <algorithm>
+
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
@@ -63,7 +65,7 @@ class AudioRendererHost::AudioEntry
   // media::AudioOutputController::EventHandler implementation.
   virtual void OnCreated() OVERRIDE;
   virtual void OnPlaying() OVERRIDE;
-  virtual void OnAudible(bool is_audible) OVERRIDE;
+  virtual void OnPowerMeasured(float power_dBFS, bool clipped) OVERRIDE;
   virtual void OnPaused() OVERRIDE;
   virtual void OnError() OVERRIDE;
   virtual void OnDeviceChange(int new_buffer_size, int new_sample_rate)
@@ -157,12 +159,13 @@ void AudioRendererHost::AudioEntry::OnPlaying() {
               stream_id_, media::AudioOutputIPCDelegate::kPlaying)));
 }
 
-void AudioRendererHost::AudioEntry::OnAudible(bool is_audible) {
+void AudioRendererHost::AudioEntry::OnPowerMeasured(float power_dBFS,
+                                                    bool clipped) {
   BrowserThread::PostTask(
       BrowserThread::IO,
       FROM_HERE,
-      base::Bind(&AudioRendererHost::DoNotifyAudibleState, host_,
-                 this, is_audible));
+      base::Bind(&AudioRendererHost::DoNotifyAudioPowerLevel, host_,
+                 this, power_dBFS, clipped));
 }
 
 void AudioRendererHost::AudioEntry::OnPaused() {
@@ -235,22 +238,38 @@ void AudioRendererHost::DoCompleteCreation(AudioEntry* entry) {
       media::PacketSizeInBytes(entry->shared_memory()->requested_size())));
 }
 
-void AudioRendererHost::DoNotifyAudibleState(AudioEntry* entry,
-                                             bool is_audible) {
+void AudioRendererHost::DoNotifyAudioPowerLevel(AudioEntry* entry,
+                                                float power_dBFS,
+                                                bool clipped) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   MediaObserver* const media_observer =
       GetContentClient()->browser()->GetMediaObserver();
   if (media_observer) {
-    DVLOG(1) << "AudioRendererHost@" << this
-             << "::DoNotifyAudibleState(is_audible=" << is_audible
-             << ") for stream_id=" << entry->stream_id();
+#ifndef NDEBUG

[DaleCurtis, 2013/07/02 22:26:34]

As nice as it looks, you should probably remove prior to commit.

[miu, 2013/07/09 00:59:56]

Done.

+    // Convenient debug tool: A simple text-mode power meter.
+    if (VLOG_IS_ON(2)) {
+      static const int kNumBars = 24;
+      static const float kBottomThreshold = -72.0f;
+      const float capped_power =
+          std::max(kBottomThreshold, std::min(0.0f, power_dBFS));
+      const int bars_lit = static_cast<int>(
+          kNumBars * (1.0f - (capped_power / kBottomThreshold)));
+      DVLOG(2) << "AudioRendererHost@" << this
+               << "::DoNotifyAudioPowerLevel("
+               << std::string(bars_lit, '#')
+               << std::string(kNumBars - bars_lit, '_')
+               << (clipped ? "!!!  " : "  ")
+               << static_cast<int>(power_dBFS) << " dBFS"
+               << ") for stream_id=" << entry->stream_id();
+    }
+#endif
 
     if (CommandLine::ForCurrentProcess()->HasSwitch(
             switches::kEnableAudibleNotifications)) {
       media_observer->OnAudioStreamPlayingChanged(
           render_process_id_, entry->render_view_id(), entry->stream_id(),
-          is_audible);
+          true, power_dBFS, clipped);
     }
   }
 }
@@ -427,7 +446,8 @@ void AudioRendererHost::DeleteEntry(scoped_ptr<AudioEntry> entry) {
       GetContentClient()->browser()->GetMediaObserver();
   if (media_observer) {
     media_observer->OnAudioStreamPlayingChanged(
-        render_process_id_, entry->render_view_id(), entry->stream_id(), false);
+        render_process_id_, entry->render_view_id(), entry->stream_id(),
+        false, -std::numeric_limits<float>::infinity(), false);
   }
 
   // Notify the media observer.