[PresentationAPI] Ensures only one pending message callback at a time if a frame created multiple s…

content/renderer/presentation/presentation_dispatcher.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 CONTENT_RENDERER_PRESENTATION_PRESENTATION_DISPATCHER_H_
 #define CONTENT_RENDERER_PRESENTATION_PRESENTATION_DISPATCHER_H_
 
 #include "base/compiler_specific.h"
 #include "base/id_map.h"
 #include "base/memory/linked_ptr.h"
@@ skipping 75 matching lines @@
       presentation::PresentationSessionState session_state);
   void OnSessionMessagesReceived(
       mojo::Array<presentation::SessionMessagePtr> messages);
   void DoSendMessage(const presentation::SessionMessage& session_message);
   void HandleSendMessageRequests(bool success);
 
   void ConnectToPresentationServiceIfNeeded();
 
   void UpdateListeningState();
 
+  void StartListenForMessages();
+
   // Used as a weak reference. Can be null since lifetime is bound to the frame.
   blink::WebPresentationController* controller_;
   presentation::PresentationServicePtr presentation_service_;
   mojo::Binding<presentation::PresentationServiceClient> binding_;
 
   // Message requests are queued here and only one message at a time is sent
   // over mojo channel.
   using MessageRequestQueue =
       std::queue<linked_ptr<presentation::SessionMessage>>;
   MessageRequestQueue message_request_queue_;
 
   enum class ListeningState {
     Inactive,
     Waiting,
     Active,
   };
 
   ListeningState listening_state_;
   bool last_known_availability_;
 
   using AvailabilityCallbacksMap =
       IDMap<blink::WebPresentationAvailabilityCallbacks, IDMapOwnPointer>;
   AvailabilityCallbacksMap availability_callbacks_;
 
   using AvailabilityObserversSet =
       std::set<blink::WebPresentationAvailabilityObserver*>;
   AvailabilityObserversSet availability_observers_;
 
+  bool listening_for_messages_;
+
   DISALLOW_COPY_AND_ASSIGN(PresentationDispatcher);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_PRESENTATION_PRESENTATION_DISPATCHER_H_