[Media Router] Reland: MediaRouter interfaces with stub implementations.

chrome/browser/media/router/media_route.h

Index: chrome/browser/media/router/media_route.h
diff --git a/chrome/browser/media/router/media_route.h b/chrome/browser/media/router/media_route.h
index a8564f63d0449be3e7080ceed2bf795fcb69b8f7..1769a57ee5af613037cca8c92d5b8e3a5b569c4b 100644
--- a/chrome/browser/media/router/media_route.h
+++ b/chrome/browser/media/router/media_route.h
@@ -17,10 +17,6 @@
 
 namespace media_router {
 
-using RouteRequestId = int64;
-
-class MediaRouteFactory;
-
 // For now, a simple transition graph: NEW -> CONNECTED -> CLOSED.
 enum MediaRouteState {
   // The route is new and not yet connected to a sink.
@@ -48,7 +44,6 @@ class MediaRoute {
              const MediaSink& media_sink,
              const std::string& description,
              bool is_local);
-
   ~MediaRoute();
 
   // The media route identifier.
@@ -75,12 +70,12 @@ class MediaRoute {
   bool Equals(const MediaRoute& other) const;
 
  private:
-  const MediaRouteId media_route_id_;
-  const MediaSource media_source_;
-  const MediaSink media_sink_;
-  const std::string description_;
-  const bool is_local_;
-  const MediaRouteState state_;
+  MediaRouteId media_route_id_;
+  MediaSource media_source_;
+  MediaSink media_sink_;
+  std::string description_;
+  bool is_local_;
+  MediaRouteState state_;
 };
 
 }  // namespace media_router