Do not show the activity widget in ActivityManager::AddActivity

athena/activity/activity_manager_impl.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.
 
 #include "athena/activity/public/activity_manager.h"
 
 #include <vector>
 
 #include "base/macros.h"
 #include "base/observer_list.h"
+#include "ui/views/widget/widget_observer.h"
 
 namespace athena {
 
 class ActivityManagerObserver;
 
-class ActivityManagerImpl : public ActivityManager {
+class ActivityManagerImpl : public ActivityManager,
+                            public views::WidgetObserver {
  public:
   ActivityManagerImpl();
   virtual ~ActivityManagerImpl();
 
   int num_activities() const { return activities_.size(); }
 
   // ActivityManager:
   virtual void AddActivity(Activity* activity) OVERRIDE;
   virtual void RemoveActivity(Activity* activity) OVERRIDE;
   virtual void UpdateActivity(Activity* activity) OVERRIDE;
   virtual void AddObserver(ActivityManagerObserver* observer) OVERRIDE;
   virtual void RemoveObserver(ActivityManagerObserver* observer) OVERRIDE;
 
+  // views::WidgetObserver
+  virtual void OnWidgetDestroying(views::Widget* widget) OVERRIDE;
+
  private:
   std::vector<Activity*> activities_;
 
   ObserverList<ActivityManagerObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(ActivityManagerImpl);
 };
 
 }  // namespace athena