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

chrome/browser/media/router/media_router_mojo_impl.h

Index: chrome/browser/media/router/media_router_mojo_impl.h
diff --git a/chrome/browser/media/router/media_router_mojo_impl.h b/chrome/browser/media/router/media_router_mojo_impl.h
index 723163ec4d159197a67664a3b28b7c95c26d0eb2..1e63be5678830f68e5567f7ca7b3f334a585a9ea 100644
--- a/chrome/browser/media/router/media_router_mojo_impl.h
+++ b/chrome/browser/media/router/media_router_mojo_impl.h
@@ -77,16 +77,7 @@ class MediaRouterMojoImpl : public MediaRouter,
       const MediaRoute::Id& route_id,
       scoped_ptr<std::vector<uint8>> data,
       const SendRouteMessageCallback& callback) override;
-  void ListenForRouteMessages(
-      const std::vector<MediaRoute::Id>& route_ids,
-      const PresentationSessionMessageCallback& message_cb) override;
   void ClearIssue(const Issue::Id& issue_id) override;
-  void RegisterMediaSinksObserver(MediaSinksObserver* observer) override;
-  void UnregisterMediaSinksObserver(MediaSinksObserver* observer) override;
-  void RegisterMediaRoutesObserver(MediaRoutesObserver* observer) override;
-  void UnregisterMediaRoutesObserver(MediaRoutesObserver* observer) override;
-  void RegisterIssuesObserver(IssuesObserver* observer) override;
-  void UnregisterIssuesObserver(IssuesObserver* observer) override;
 
   const std::string& media_route_provider_extension_id() const {
     return media_route_provider_extension_id_;
@@ -100,6 +91,12 @@ class MediaRouterMojoImpl : public MediaRouter,
   friend class MediaRouterFactory;
   friend class MediaRouterMojoTest;
 
+  FRIEND_TEST_ALL_PREFIXES(MediaRouterMojoImplTest,
+                           RegisterAndUnregisterMediaSinksObserver);
+  FRIEND_TEST_ALL_PREFIXES(MediaRouterMojoImplTest,
+                           RegisterAndUnregisterMediaRoutesObserver);
+  FRIEND_TEST_ALL_PREFIXES(MediaRouterMojoImplTest,
+                           HandleIssue);
   FRIEND_TEST_ALL_PREFIXES(MediaRouterMojoExtensionTest,
                            DeferredBindingAndSuspension);
 
@@ -125,6 +122,18 @@ class MediaRouterMojoImpl : public MediaRouter,
   // Dispatches the Mojo requests queued in |pending_requests_|.
   void ExecutePendingRequests();
 
+  // MediaRouter implementation.
+  void RegisterMediaSinksObserver(MediaSinksObserver* observer) override;
+  void UnregisterMediaSinksObserver(MediaSinksObserver* observer) override;
+  void RegisterMediaRoutesObserver(MediaRoutesObserver* observer) override;
+  void UnregisterMediaRoutesObserver(MediaRoutesObserver* observer) override;
+  void RegisterIssuesObserver(IssuesObserver* observer) override;
+  void UnregisterIssuesObserver(IssuesObserver* observer) override;
+  void RegisterPresentationSessionMessagesObserver(
+      PresentationSessionMessagesObserver* observer) override;
+  void UnregisterPresentationSessionMessagesObserver(
+      PresentationSessionMessagesObserver* observer) override;
+
   // These calls invoke methods in the component extension via Mojo.
   void DoCreateRoute(const MediaSource::Id& source_id,
                      const MediaSink::Id& sink_id,
@@ -143,9 +152,7 @@ class MediaRouterMojoImpl : public MediaRouter,
   void DoSendSessionBinaryMessage(const MediaRoute::Id& route_id,
                                   scoped_ptr<std::vector<uint8>> data,
                                   const SendRouteMessageCallback& callback);
-  void DoListenForRouteMessages(
-      const std::vector<MediaRoute::Id>& route_ids,
-      const PresentationSessionMessageCallback& message_cb);
+  void DoListenForRouteMessages(const MediaRoute::Id& route_id);
   void DoClearIssue(const Issue::Id& issue_id);
   void DoStartObservingMediaSinks(const MediaSource::Id& source_id);
   void DoStopObservingMediaSinks(const MediaSource::Id& source_id);
@@ -153,10 +160,10 @@ class MediaRouterMojoImpl : public MediaRouter,
   void DoStopObservingMediaRoutes();
 
   // Invoked when the next batch of messages arrives.
+  // |route_id|: ID of route of the messages.
   // |messages|: A list of messages received.
-  // |message_cb|: The callback to invoke to pass on the messages received.
-  void OnRouteMessageReceived(
-      const PresentationSessionMessageCallback& message_cb,
+  void OnRouteMessagesReceived(
+      const MediaRoute::Id& route_id,
       mojo::Array<interfaces::RouteMessagePtr> messages);
 
   // Error handler callback for |binding_| and |media_route_provider_|.
@@ -182,6 +189,16 @@ class MediaRouterMojoImpl : public MediaRouter,
 
   base::ObserverList<MediaRoutesObserver> routes_observers_;
 
+  base::ScopedPtrHashMap<
+      MediaRoute::Id,
+      scoped_ptr<base::ObserverList<PresentationSessionMessagesObserver>>>

[mark a. foltz, 2015/08/04 23:47:02]

Consider a using declaration for PresentationSessionMessagesObserverList.

[imcheng, 2015/08/05 21:38:35]

Done.

+      messages_observers_;
+  // IDs of MediaRoutes being listened for messages. Note that this is
+  // different from |message_observers_| because we might be waiting for
+  // |OnRouteMessagesReceived()| to be invoked after all observers for that
+  // route have been removed.
+  base::hash_set<MediaRoute::Id> listening_messages_for_routes_;

[mark a. foltz, 2015/08/04 23:47:02]

I think std::set would use a little less memory (no empty buckets).  But you
might check my reasoning on that.

Also route_ids_listening_for_messages_?

[imcheng, 2015/08/05 21:38:35]

Done.

+
   IssueManager issue_manager_;
 
   // Binds |this| to a Mojo connection stub for interfaces::MediaRouter.