Revert of Revert of Propagate audible state from player to the containing tab"

content/browser/media/audio_stream_monitor.cc

Index: content/browser/media/audio_stream_monitor.cc
diff --git a/content/browser/media/audio_stream_monitor.cc b/content/browser/media/audio_stream_monitor.cc
index 1d2f76f7f2c02f986f5b52122834363ff96be1e8..4c0bc0a5d720c6ce0debbadd6587ac96b8a0fa75 100644
--- a/content/browser/media/audio_stream_monitor.cc
+++ b/content/browser/media/audio_stream_monitor.cc
@@ -21,23 +21,36 @@ AudioStreamMonitor* AudioStreamMonitorFromRenderFrame(int render_process_id,
   WebContentsImpl* const web_contents =
       static_cast<WebContentsImpl*>(WebContents::FromRenderFrameHost(
           RenderFrameHost::FromID(render_process_id, render_frame_id)));
-  return web_contents ? web_contents->audio_stream_monitor() : NULL;
+
+  if (!web_contents)
+    return nullptr;
+
+  AudioStateProvider* audio_provider = web_contents->audio_state_provider();
+  return audio_provider ? audio_provider->audio_stream_monitor() : nullptr;
 }
 
 }  // namespace
 
 AudioStreamMonitor::AudioStreamMonitor(WebContents* contents)
-    : web_contents_(contents),
-      clock_(&default_tick_clock_),
-      was_recently_audible_(false) {
-  DCHECK(web_contents_);
+    : AudioStateProvider(contents),
+      clock_(&default_tick_clock_)
+{
 }
 
 AudioStreamMonitor::~AudioStreamMonitor() {}
 
+bool AudioStreamMonitor::IsAudioStateAvailable() const {
+  return media::AudioOutputController::will_monitor_audio_levels();
+}
+
+// This provider is the monitor.
+AudioStreamMonitor* AudioStreamMonitor::audio_stream_monitor() {
+  return this;
+}
+
 bool AudioStreamMonitor::WasRecentlyAudible() const {
   DCHECK(thread_checker_.CalledOnValidThread());
-  return was_recently_audible_;
+  return AudioStateProvider::WasRecentlyAudible();
 }
 
 // static
@@ -46,7 +59,7 @@ void AudioStreamMonitor::StartMonitoringStream(
     int render_frame_id,
     int stream_id,
     const ReadPowerAndClipCallback& read_power_callback) {
-  if (!monitoring_available())
+  if (!media::AudioOutputController::will_monitor_audio_levels())
     return;
   BrowserThread::PostTask(BrowserThread::UI,
                           FROM_HERE,
@@ -61,7 +74,7 @@ void AudioStreamMonitor::StartMonitoringStream(
 void AudioStreamMonitor::StopMonitoringStream(int render_process_id,
                                               int render_frame_id,
                                               int stream_id) {
-  if (!monitoring_available())
+  if (!media::AudioOutputController::will_monitor_audio_levels())
     return;
   BrowserThread::PostTask(BrowserThread::UI,
                           FROM_HERE,
@@ -138,16 +151,12 @@ void AudioStreamMonitor::Poll() {
 }
 
 void AudioStreamMonitor::MaybeToggle() {
-  const bool indicator_was_on = was_recently_audible_;
   const base::TimeTicks off_time =
       last_blurt_time_ + base::TimeDelta::FromMilliseconds(kHoldOnMilliseconds);
   const base::TimeTicks now = clock_->NowTicks();
   const bool should_indicator_be_on = now < off_time;
 
-  if (should_indicator_be_on != indicator_was_on) {
-    was_recently_audible_ = should_indicator_be_on;
-    web_contents_->NotifyNavigationStateChanged(INVALIDATE_TYPE_TAB);
-  }
+  Notify(should_indicator_be_on);
 
   if (!should_indicator_be_on) {
     off_timer_.Stop();