Adding Baseframework of the ResourceManager (all hooks and observers) are being put in place with a…

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"
 
 namespace athena {
 
+class ActivityManagerObserver;
+
 class ActivityManagerImpl : public ActivityManager {
  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;
 
  private:
   std::vector<Activity*> activities_;
 
+  ObserverList<ActivityManagerObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(ActivityManagerImpl);
 };
 
 }  // namespace athena