athena: Use ActivityList where appropriate, and fix AppActivity tests.

athena/content/app_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_APP_ACTIVITY_H_
 #define ATHENA_CONTENT_APP_ACTIVITY_H_
 
 #include "athena/activity/public/activity.h"
 #include "athena/activity/public/activity_view_model.h"
 #include "athena/content/app_activity_proxy.h"
@@ skipping 39 matching lines @@
   gfx::ImageSkia GetOverviewModeImage() override;
   void PrepareContentsForOverview() override;
   void ResetContentsView() override;
 
  protected:
   // Constructor for test.
   explicit AppActivity(const std::string& app_id);
 
   ~AppActivity() override;
 
+  // Register this activity with its application.
+  void RegisterActivity();
+
+  AppActivityRegistry* app_activity_registry() {
+    return app_activity_registry_;
+  }
+
  private:
  // content::WebContentsObserver:
   void TitleWasSet(content::NavigationEntry* entry, bool explicit_set) override;
   void DidUpdateFaviconURL(
       const std::vector<content::FaviconURL>& candidates) override;
 
-  // Register this activity with its application.
-  void RegisterActivity();
-
   // Hiding the contet proxy and showing the real content instead.
   void HideContentProxy();
 
   // Showing a content proxy instead of the real content to save resources.
   void ShowContentProxy();
 
   const std::string app_id_;
 
   views::WebView* web_view_;
 
@@ skipping 12 matching lines @@
   // destroyed before the activity, then it must be reset using
   // SetActivityView(nullptr).
   ActivityView* activity_view_;
 
   DISALLOW_COPY_AND_ASSIGN(AppActivity);
 };
 
 }  // namespace athena
 
 #endif  // ATHENA_CONTENT_APP_ACTIVITY_H_