Gardening: Revert "Use AudioStreamMonitor to control power save blocking."

content/public/browser/media_observer.h

Index: content/public/browser/media_observer.h
diff --git a/content/public/browser/media_observer.h b/content/public/browser/media_observer.h
index 6e7088b1c184a299070512db5be73e2e8fdd1e09..321e7d0f14c628d8c00c97debd6e16099084aefe 100644
--- a/content/public/browser/media_observer.h
+++ b/content/public/browser/media_observer.h
@@ -34,6 +34,27 @@ class MediaObserver {
   virtual void OnCreatingAudioStream(int render_process_id,
                                      int render_frame_id) = 0;
 
+  // Called when an audio stream transitions into a playing state.
+  // |power_read_callback| is a thread-safe callback, provided for polling the
+  // current audio signal power level, and any copies/references to it must be
+  // destroyed when OnAudioStreamStopped() is called.
+  //
+  // The callback returns the current power level (in dBFS units) and the clip
+  // status (true if any part of the audio signal has clipped since the last
+  // callback run).  See media/audio/audio_power_monitor.h for more info.
+  typedef base::Callback<std::pair<float, bool>()> ReadPowerAndClipCallback;
+  virtual void OnAudioStreamPlaying(
+      int render_process_id,
+      int render_frame_id,
+      int stream_id,
+      const ReadPowerAndClipCallback& power_read_callback) = 0;
+
+  // Called when an audio stream has stopped.
+  virtual void OnAudioStreamStopped(
+      int render_process_id,
+      int render_frame_id,
+      int stream_id) = 0;
+
  protected:
   virtual ~MediaObserver() {}
 };