[MediaRouter] The minimal change to make everything build on Android.

chrome/browser/ui/toolbar/media_router_action.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_TOOLBAR_MEDIA_ROUTER_ACTION_H_
 #define CHROME_BROWSER_UI_TOOLBAR_MEDIA_ROUTER_ACTION_H_
 
 #include "chrome/browser/ui/toolbar/toolbar_action_view_controller.h"
 
 class Browser;
 class MediaRouterActionPlatformDelegate;
 
 namespace media_router {
-class MediaRouterDialogController;
+class MediaRouterDialogControllerImpl;
 }  // namespace media_router
 
 // The class for the Media Router component action that will be shown in
 // the toolbar.
 class MediaRouterAction : public ToolbarActionViewController {
  public:
   explicit MediaRouterAction(Browser* browser);
   ~MediaRouterAction() override;
 
   // ToolbarActionViewController implementation.
@@ skipping 14 matching lines @@
   ui::MenuModel* GetContextMenu() override;
   bool CanDrag() const override;
   bool ExecuteAction(bool by_user) override;
   void UpdateState() override;
   bool DisabledClickOpensMenu() const override;
 
  private:
   // Returns a reference to the MediaRouterDialogController associated with
   // |delegate_|'s current WebContents. Guaranteed to be non-null.
   // |delegate_| and its current WebContents must not be null.
-  media_router::MediaRouterDialogController* GetMediaRouterDialogController();

[mark a. foltz, 2015/07/22 21:16:39]

Why does this API need to be changed to use the implementation type?

[whywhat, 2015/07/22 22:55:01]

Well, I assumed that webui/ classes can use the webui specific Impl class. That
way webui/ specific methods can be added to the Impl class and accessed from
other webui/ classes. These methods (e.g. about dialog's WebContents) won't even
make sense on Android so I don't want to drag them out into the base class.

Also, this made the impact on the webui/ code minimal.

However, it seems to only use Show and Close MediaRouterDialog methods so I
could use the base class. I'll look into it in my follow-up change.

[mark a. foltz, 2015/07/22 23:05:55]

Okay, if the methods make sense in the MediaRouterDialog class then I would
prefer you move them up and revert this change.  Otherwise it's not a big deal.

In general I prefer APIs that return interface types instead of implementation
types, because exposing implementation types makes unit testing and future
refactoring harder.

+  media_router::MediaRouterDialogControllerImpl*
+      GetMediaRouterDialogController();
 
   const std::string id_;
   const base::string16 name_;
 
   // Cached icons.
   gfx::Image media_router_idle_icon_;
 
   ToolbarActionViewDelegate* delegate_;
 
   // The delegate to handle platform-specific implementations.
   scoped_ptr<MediaRouterActionPlatformDelegate> platform_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaRouterAction);
 };
 
 #endif  // CHROME_BROWSER_UI_TOOLBAR_MEDIA_ROUTER_ACTION_H_