athena: Introduce ActivityView.

athena/content/web_activity.h

 // Copyright 2014 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 ATHENA_CONTENT_PUBLIC_WEB_ACTIVITY_H_
 #define ATHENA_CONTENT_PUBLIC_WEB_ACTIVITY_H_
 
 #include <vector>
 
 #include "athena/activity/public/activity.h"
@@ skipping 44 matching lines @@
   bool IsVisible() override;
   ActivityMediaState GetMediaState() override;
   aura::Window* GetWindow() override;
   content::WebContents* GetWebContents() override;
 
   // ActivityViewModel:
   void Init() override;
   SkColor GetRepresentativeColor() const override;
   base::string16 GetTitle() const override;
   gfx::ImageSkia GetIcon() const override;
+  void SetActivityView(ActivityView* activity_view) override;
   bool UsesFrame() const override;
   views::View* GetContentsView() override;
   gfx::ImageSkia GetOverviewModeImage() override;
   void PrepareContentsForOverview() override;
   void ResetContentsView() override;
 
   // content::WebContentsObserver:
   void DidNavigateMainFrame(
       const content::LoadCommittedDetails& details,
       const content::FrameNavigateParams& params) override;
@@ skipping 23 matching lines @@
   const base::string16 title_;
   SkColor title_color_;
   gfx::ImageSkia icon_;
 
   // The current state for this activity.
   ActivityState current_state_;
 
   // The content proxy.
   scoped_ptr<ContentProxy> content_proxy_;
 
+  // WebActivity does not take ownership of |activity_view_|. If the view is
+  // destroyed before the activity, then it must be reset using
+  // SetActivityView(nullptr).
+  ActivityView* activity_view_;
+
   base::WeakPtrFactory<WebActivity> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WebActivity);
 };
 
 }  // namespace athena
 
 #endif  // ATHENA_CONTENT_WEB_ACTIVITY_H_