[Media Router] 2nd take on fix route response callback lifetime in UI.

chrome/browser/ui/webui/media_router/media_router_dialog_controller.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_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_DIALOG_CONTROLLER_H_
 #define CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_DIALOG_CONTROLLER_H_
 
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"

[mark a. foltz, 2015/07/14 21:36:32]

Not used

 #include "chrome/browser/media/router/create_session_request.h"
+#include "chrome/browser/media/router/media_router.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 
 namespace media_router {
 
 // An instance of this class is tied to a WebContents known as the initiator,
 // and is lazily created when a Media Router dialog needs to be shown.
 // The MediaRouterDialogController allows creating, querying, and removing a
 // Media Router dialog modal to the initiator WebContents.
 // This class is not thread safe and must be called on the UI thread.
@@ skipping 23 matching lines @@
       scoped_ptr<CreateSessionRequest> request);
 
   // Returns the media router dialog WebContents.
   // Returns nullptr if there is no dialog.
   content::WebContents* GetMediaRouterDialog() const;
 
   // Closes the media router dialog. This will destroy the dialog WebContents.
   // It is an error to call this function if there is currently no dialog.
   void CloseMediaRouterDialog();
 
+  // Called by the dialog when it is about to make a presentation route request

[haibinlu, 2015/07/14 01:44:55]

create route

[imcheng, 2015/07/14 16:45:37]

This is specific to presentation route requests.

+  // to ensure the response can be received and handled properly even when
+  // the dialog is destroyed while the request is in progress.
+  // Returns a MediaRouteResponseCallback that can be used to be used as the
+  // callback argument in |MediaRouter::CreateRoute()|.
+  // |route_response_callback|: Callback to the dialog to invoke when the
+  // presentation route response comes back, if the dialog still exists.
+  // |presentation_request|: The Presentation API request to respond to when
+  // route reponse comes back, or nullptr if the request did not originate from
+  // Presentation API.

[mark a. foltz, 2015/07/14 21:36:32]

The comment above suggests that this is only for Presentation API - so
|presentation_request| cannot be nullptr?  Or do you intend for the API to
handle both Presentation and non-Presentation use cases (which seems better)? 
Please clarify.

+  MediaRouteResponseCallback AddPresentationRouteRequest(
+      const MediaRouteResponseCallback& route_response_callback,
+      scoped_ptr<CreateSessionRequest> presentation_request);

[mark a. foltz, 2015/07/14 21:36:32]

CreateSessionRequest -> CreatePresentationSessionRequest ?

[imcheng, 2015/07/16 01:06:52]

Done.

+
  private:
+  class BrowserInitiatedCallbacks;
   class DialogWebContentsObserver;
   class InitiatorWebContentsObserver;
+  class MediaRouterDialogCallbacks;
+  class PresentationInitiatedCallbacks;
   friend class content::WebContentsUserData<MediaRouterDialogController>;
 
   // Use MediaRouterDialogController::CreateForWebContents() to create an
   // instance.
   explicit MediaRouterDialogController(content::WebContents* web_contents);
 
   // Creates a new media router dialog modal to |initiator_|.
   void CreateMediaRouterDialog();
 
   // Resets this dialog controller to an empty state.
   void Reset();
 
   // Invoked when the dialog WebContents has navigated.
   void OnDialogNavigated(const content::LoadCommittedDetails& details);
 
   void PopulateDialog(content::WebContents* media_router_dialog);
 
+  // Destroys |callbacks| by removing it from |pending_dialog_callbacks_|.
+  // Called by MediaRouterDialogCallbacks after it receives route response and
+  // is done processing it.
+  // |callbacks|: The MediaRouterDialogCallbacks to destroy.
+  void DestroyDialogCallbacks(MediaRouterDialogCallbacks* callbacks);

[mark a. foltz, 2015/07/14 21:36:32]

This might be better named RemoveDialogCallbacks()?  When I first read this I
thought it was just a method to invoke the MRDC destructor.

+
   scoped_ptr<InitiatorWebContentsObserver> initiator_observer_;
   scoped_ptr<DialogWebContentsObserver> dialog_observer_;
 
   content::WebContents* const initiator_;
 
   // True if the controller is waiting for a new media router dialog to be
   // created.
   bool media_router_dialog_pending_;
 
   // Data for dialogs created under a Presentation API context.
   // Passed from the caller of ShowMediaRouterDialogForPresentation(), and
   // passed to the MediaRouterUI when it is initialized.
   scoped_ptr<CreateSessionRequest> presentation_request_;
 
+  // MediaRouterDialogCallbacks corresponding to presentation route requests

[haibinlu, 2015/07/14 01:44:55]

create route requests

[imcheng, 2015/07/14 16:45:37]

ditto

+  // made from dialogs created from this instance. Note that they may outlive
+  // their corresponding dialogs.
+  ScopedVector<MediaRouterDialogCallbacks> pending_dialog_callbacks_;
+
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaRouterDialogController);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_DIALOG_CONTROLLER_H_