Revert, causing browser crashes due to race

content/browser/renderer_host/media/peer_connection_tracker_host.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_PEER_CONNECTION_TRACKER_HOST_H_
 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_PEER_CONNECTION_TRACKER_HOST_H_
 
-#include "base/power_monitor/power_observer.h"
 #include "content/public/browser/browser_message_filter.h"
 
 struct PeerConnectionInfo;
 
 namespace base {
 class ListValue;
 }  // namespace base
 
 namespace content {
 
 // This class is the host for PeerConnectionTracker in the browser process
-// managed by RenderProcessHostImpl. It receives PeerConnection events from
-// PeerConnectionTracker as IPC messages that it forwards to WebRTCInternals.
-// It also forwards browser process events to PeerConnectionTracker via IPC.
-class PeerConnectionTrackerHost : public BrowserMessageFilter,
-                                  public base::PowerObserver {
+// managed by RenderProcessHostImpl. It passes IPC messages between
+// WebRTCInternals and PeerConnectionTracker.
+class PeerConnectionTrackerHost : public BrowserMessageFilter {
  public:
   PeerConnectionTrackerHost(int render_process_id);
 
   // content::BrowserMessageFilter override.
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
   virtual void OverrideThreadForMessage(const IPC::Message& message,
                                         BrowserThread::ID* thread) OVERRIDE;
 
-  // base::PowerObserver override.
-  virtual void OnSuspend() OVERRIDE;
-
  protected:
   virtual ~PeerConnectionTrackerHost();
 
  private:
   // Handlers for peer connection messages coming from the renderer.
   void OnAddPeerConnection(const PeerConnectionInfo& info);
   void OnRemovePeerConnection(int lid);
   void OnUpdatePeerConnection(
       int lid, const std::string& type, const std::string& value);
   void OnAddStats(int lid, const base::ListValue& value);
   void OnGetUserMedia(const std::string& origin,
                       bool audio,
                       bool video,
                       const std::string& audio_constraints,
                       const std::string& video_constraints);
 
   int render_process_id_;
 
   DISALLOW_COPY_AND_ASSIGN(PeerConnectionTrackerHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_PEER_CONNECTION_TRACKER_HOST_H_