Show the Cast toolbar icon ephemerally when Cast is in use

chrome/browser/ui/webui/media_router/media_router_dialog_controller_impl.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_IMPL_H_
 #define CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_DIALOG_CONTROLLER_IMPL_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/scoped_observer.h"
 #include "chrome/browser/media/router/media_router_dialog_controller.h"
+#include "chrome/browser/ui/tabs/tab_strip_model_observer.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 
 FORWARD_DECLARE_TEST(MediaRouterActionUnitTest, IconPressedState);
 
 class MediaRouterAction;
 
 namespace media_router {
 
 // A desktop implementation of MediaRouterDialogController.
 // This class is not thread safe and must be called on the UI thread.
 class MediaRouterDialogControllerImpl :
     public content::WebContentsUserData<MediaRouterDialogControllerImpl>,
-    public MediaRouterDialogController {
+    public MediaRouterDialogController,
+    public TabStripModelObserver {
  public:
   ~MediaRouterDialogControllerImpl() override;
 
   static MediaRouterDialogControllerImpl* GetOrCreateForWebContents(
       content::WebContents* web_contents);
 
   // Returns the media router dialog WebContents.
   // Returns nullptr if there is no dialog.
   content::WebContents* GetMediaRouterDialog() const;
 
   // |action| must always be non-null.
   void SetMediaRouterAction(const base::WeakPtr<MediaRouterAction>& action);
 
+  void UpdateMaxDialogSize();
+
   // MediaRouterDialogController:
   bool IsShowingMediaRouterDialog() const override;
+  bool ShowMediaRouterDialog() override;
 
-  void UpdateMaxDialogSize();
+  // ToolbarStripModelObserver:
+  void ActiveTabChanged(content::WebContents* old_contents,
+                        content::WebContents* new_contents,
+                        int index,
+                        int reason) override;
+
+  MediaRouterAction* action_for_test() { return action_.get(); }
 
  private:
   class DialogWebContentsObserver;
   friend class content::WebContentsUserData<MediaRouterDialogControllerImpl>;
   FRIEND_TEST_ALL_PREFIXES(::MediaRouterActionUnitTest, IconPressedState);
 
   // Use MediaRouterDialogControllerImpl::CreateForWebContents() to create an
   // instance.
   explicit MediaRouterDialogControllerImpl(content::WebContents* web_contents);
 
   // MediaRouterDialogController:
   void CreateMediaRouterDialog() override;
   void CloseMediaRouterDialog() override;
   void Reset() override;
 
   // Invoked when the dialog WebContents has navigated.
   void OnDialogNavigated(const content::LoadCommittedDetails& details);
 
   void PopulateDialog(content::WebContents* media_router_dialog);
 
+  void ShowMediaRouterAction();
+
   std::unique_ptr<DialogWebContentsObserver> dialog_observer_;
 
   // True if the controller is waiting for a new media router dialog to be
   // created.
   bool media_router_dialog_pending_;
 
+  ScopedObserver<TabStripModel, TabStripModelObserver>
+      tab_strip_model_observer_;
+
   // |action_| refers to the MediaRouterAction on the toolbar, rather than
   // overflow menu. A MediaRouterAction is always created for the toolbar
   // first. Any subsequent creations for the overflow menu will not be set as
   // |action_|.
   // The lifetime of |action_| is dependent on the creation and destruction of
   // a browser window. The overflow menu's MediaRouterAction is only created
   // when the overflow menu is opened and destroyed when the menu is closed.
   base::WeakPtr<MediaRouterAction> action_;
 
   base::WeakPtrFactory<MediaRouterDialogControllerImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaRouterDialogControllerImpl);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_DIALOG_CONTROLLER_IMPL_H_