[Media Router] Add Media Router Mojo impl code.

chrome/browser/media/router/media_sinks_observer.h

 // Copyright 2015 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 CHROME_BROWSER_MEDIA_ROUTER_MEDIA_SINKS_OBSERVER_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_SINKS_OBSERVER_H_
 
 #include <vector>
 
 #include "base/macros.h"
@@ skipping 10 matching lines @@
 // receive results. It can then interpret / process the results accordingly.
 class MediaSinksObserver {
  public:
   // Constructs an observer that will observe for sinks compatible
   // with |source|.
   MediaSinksObserver(MediaRouter* router, const MediaSource& source);
   virtual ~MediaSinksObserver();
 
   // This function is invoked when the list of sinks compatible
   // with |source_| has been updated.
+  // Implementations may not perform operations that modify the Media Router's
+  // observer list. In particular, invoking this observer's destructor within
+  // OnSinksReceived will result in undefined behavior.
   virtual void OnSinksReceived(const std::vector<MediaSink>& sinks) {}
 
   const MediaSource& source() const { return source_; }
 
  private:
   const MediaSource source_;
   MediaRouter* router_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaSinksObserver);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_MEDIA_SINKS_OBSERVER_H_