[Presentation API] Change ListenForSessionMessages API to client-style.

chrome/browser/media/router/media_route.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_ROUTE_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTE_H_
 
 #include <string>
 
 #include "base/containers/small_map.h"
@@ skipping 82 matching lines @@
   const content::PresentationSessionInfo* Get(
       const MediaRoute::Id& route_id) const;
 
  private:
   base::SmallMap<std::map<MediaRoute::Id, content::PresentationSessionInfo>>
       route_id_to_presentation_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaRouteIdToPresentationSessionMapping);
 };
 
-// Return a pair of Presentation ID and URL. If the input route ID is invalid,
-// a pair of empty strings is returned.
-std::pair<std::string, std::string> GetPresentationIdAndUrl(
-    const MediaRoute::Id& id);
-
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTE_H_