(Not for review) Dummy C++ side Custom Controls implementation

chrome/browser/media/router/mojo/media_router_mojo_impl.h

Index: chrome/browser/media/router/mojo/media_router_mojo_impl.h
diff --git a/chrome/browser/media/router/mojo/media_router_mojo_impl.h b/chrome/browser/media/router/mojo/media_router_mojo_impl.h
index 73d7187e6f62bfb30c800eb0ea41bf29b462bd12..44754cf615b4ecab38c5559dafb0277b350ebc2e 100644
--- a/chrome/browser/media/router/mojo/media_router_mojo_impl.h
+++ b/chrome/browser/media/router/mojo/media_router_mojo_impl.h
@@ -108,6 +108,12 @@ class MediaRouterMojoImpl : public MediaRouterBase,
       const std::string& search_input,
       const std::string& domain,
       const MediaSinkSearchResponseCallback& sink_callback) override;
+  MediaRouteController* GetControllerForRoute(
+      const MediaRoute::Id& route_id) override;
+
+  bool GetMediaRouteController(const MediaRoute::Id& route_id,
+                               mojom::MediaControllerRequest controller);
+  void DestroyMediaRouteController(const MediaRoute::Id& route_id);
 
   const std::string& media_route_provider_extension_id() const {
     return media_route_provider_extension_id_;
@@ -365,6 +371,11 @@ class MediaRouterMojoImpl : public MediaRouterBase,
   void UpdateMediaSinks(const MediaSource::Id& source_id);
   void DoUpdateMediaSinks(const MediaSource::Id& source_id);
 
+  // Removes controllers from |route_controllers_| whose media routes do not
+  // appear in |routes|.
+  void RemoveInvalidMediaRouteControllers(
+      const std::vector<MediaRoute>& routes);
+
   // Pending requests queued to be executed once component extension
   // becomes ready.
   std::deque<base::Closure> pending_requests_;
@@ -418,6 +429,9 @@ class MediaRouterMojoImpl : public MediaRouterBase,
   // initial event page wakeup attempt.
   bool provider_version_was_recorded_ = false;
 
+  std::unordered_map<MediaRoute::Id, std::unique_ptr<MediaRouteController>>
+      route_controllers_;
+
 #if defined(OS_WIN)
   // A pair of flags to ensure that mDNS discovery is only enabled on Windows
   // when there will be appropriate context for the user to associate a firewall