Replace AudioSilenceDetector with an AudioPowerMonitor.

chrome/browser/media/audio_stream_indicator.cc

Index: chrome/browser/media/audio_stream_indicator.cc
diff --git a/chrome/browser/media/audio_stream_indicator.cc b/chrome/browser/media/audio_stream_indicator.cc
index 6cd623212e72fcf8dcc722241af868ec291d5755..adc3b71a41e1ab77c5ac5184da3948337ea4fed4 100644
--- a/chrome/browser/media/audio_stream_indicator.cc
+++ b/chrome/browser/media/audio_stream_indicator.cc
@@ -4,6 +4,8 @@
 
 #include "chrome/browser/media/audio_stream_indicator.h"
 
+#include <limits>
+
 #include "base/bind.h"
 #include "chrome/browser/tab_contents/tab_util.h"
 #include "content/public/browser/browser_thread.h"
@@ -20,17 +22,17 @@ AudioStreamIndicator::~AudioStreamIndicator() {}
 
 void AudioStreamIndicator::UpdateWebContentsStatus(
     int render_process_id, int render_view_id, int stream_id,
-    bool is_playing_and_audible) {
+    bool is_playing, float power_in_dbfs) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&AudioStreamIndicator::UpdateWebContentsStatusOnUIThread, this,
                  render_process_id, render_view_id, stream_id,
-                 is_playing_and_audible));
+                 is_playing, power_in_dbfs));
 }
 
-bool AudioStreamIndicator::IsPlayingAudio(WebContents* contents) {
+bool AudioStreamIndicator::IsPlayingAudio(WebContents* contents) const {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   RenderViewId id(contents->GetRenderProcessHost()->GetID(),
@@ -38,6 +40,28 @@ bool AudioStreamIndicator::IsPlayingAudio(WebContents* contents) {
   return audio_streams_.find(id) != audio_streams_.end();
 }
 
+float AudioStreamIndicator::GetAudioPowerLevelInDBFS(

[DaleCurtis, 2013/05/16 18:24:45]

Seems like there should be a simpler way to do this, but I can't workout an
(accurate) running average or maximum algorithm without the added overhead for
when a stream stops playing.

[miu, 2013/05/16 21:44:11]

Acknowledged.

+    content::WebContents* contents) const {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  // Since a RenderView can have more than one stream playing back, return the
+  // maximum of the last-reported power levels.  For more information about how
+  // the power level is measured, see media/audio/audio_power_monitor.h.
+  float max_power_dbfs = -std::numeric_limits<float>::infinity();
+  RenderViewId id(contents->GetRenderProcessHost()->GetID(),
+                  contents->GetRenderViewHost()->GetRoutingID());
+  RenderViewStreamMap::const_iterator stream_it = audio_streams_.find(id);
+  if (stream_it != audio_streams_.end()) {
+    const StreamPowerLevelMap& power_levels = stream_it->second;
+    for (StreamPowerLevelMap::const_iterator power_it = power_levels.begin();
+         power_it != power_levels.end(); ++power_it) {
+      if (power_it->second > max_power_dbfs)
+        max_power_dbfs = power_it->second;
+    }
+  }
+  return max_power_dbfs;
+}
+
 AudioStreamIndicator::RenderViewId::RenderViewId(int render_process_id,
                                                  int render_view_id)
     : render_process_id(render_process_id),
@@ -56,20 +80,23 @@ void AudioStreamIndicator::UpdateWebContentsStatusOnUIThread(
     int render_process_id,
     int render_view_id,
     int stream_id,
-    bool is_playing_and_audible) {
+    bool is_playing,
+    float power_in_dbfs) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   RenderViewId id(render_process_id, render_view_id);
-  if (is_playing_and_audible) {
-    audio_streams_[id].insert(stream_id);
+  if (is_playing) {
+    audio_streams_[id][stream_id] = power_in_dbfs;
   } else {
-    std::map<RenderViewId, std::set<int> >::iterator it =
-        audio_streams_.find(id);
-    if (it == audio_streams_.end())
+    RenderViewStreamMap::iterator stream_it = audio_streams_.find(id);
+    if (stream_it == audio_streams_.end())
       return;
-
-    it->second.erase(stream_id);
-    if (it->second.empty())
-      audio_streams_.erase(it);
+    StreamPowerLevelMap& power_levels = stream_it->second;
+    StreamPowerLevelMap::iterator power_it = power_levels.find(stream_id);
+    if (power_it == power_levels.end())
+      return;
+    power_levels.erase(power_it);
+    if (power_levels.empty())
+      audio_streams_.erase(stream_it);
   }
 
   WebContents* web_contents = tab_util::GetWebContentsByID(render_process_id,