[SystemInfo API] Implement systemInfo.storage.onAvailableCapacityChanged event

chrome/browser/extensions/system_info_event_router.h

 // Copyright (c) 2012 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_EXTENSIONS_SYSTEM_INFO_EVENT_ROUTER_H_
 #define CHROME_BROWSER_EXTENSIONS_SYSTEM_INFO_EVENT_ROUTER_H_
 
 #include <set>
 
 #include "base/file_path.h"
 #include "base/memory/singleton.h"
 #include "base/values.h"
+#include "chrome/browser/extensions/api/system_info_storage/storage_info_observer.h"
 
 namespace extensions {
 
 namespace api {
 
 namespace experimental_system_info_cpu {
 
 struct CpuUpdateInfo;
 
 }  // namespace experimental_system_info_cpu
 
 }  // namespace api
 
 // Event router for systemInfo API. It is a singleton instance shared by
 // multiple profiles.
 // TODO(hongbo): It should derive from SystemMonitor::DevicesChangedObserver.
 // Since the system_monitor will be refactored along with media_gallery, once
 // http://crbug.com/145400 is fixed, we need to update SystemInfoEventRouter
 // accordingly.
-class SystemInfoEventRouter {
+class SystemInfoEventRouter : public StorageInfoObserver {
  public:
   static SystemInfoEventRouter* GetInstance();
 
   // Add/remove event listener for the |event_name| event from |profile|.
   void AddEventListener(const std::string& event_name);
   void RemoveEventListener(const std::string& event_name);
 
   // Return true if the |event_name| is an event from systemInfo namespace.
   static bool IsSystemInfoEvent(const std::string& event_name);
 
+  // StorageInfoObserver implementation:
+  virtual void OnStorageFreeSpaceChanged(const std::string& id,
+                                         double new_value,
+                                         double old_value);
+
   // TODO(hongbo): The following methods should be likely overriden from
   // SystemMonitor::DevicesChangedObserver once the http://crbug.com/145400
   // is fixed.
-  void OnStorageAvailableCapacityChanged(const std::string& id,
-                                         int64 available_capacity);
   void OnRemovableStorageAttached(const std::string& id,
                                   const string16& name,
                                   const FilePath::StringType& location);
   void OnRemovableStorageDetached(const std::string& id);
 
  private:
   friend struct DefaultSingletonTraits<SystemInfoEventRouter>;
 
   SystemInfoEventRouter();
   virtual ~SystemInfoEventRouter();
 
   // Called from any thread to dispatch the systemInfo event to all extension
   // processes cross multiple profiles.
   void DispatchEvent(const std::string& event_name,
       scoped_ptr<base::ListValue> args);
 
   // The callback for CPU sampling cycle. Called from FILE thread.
   void OnNextCpuSampling(
       scoped_ptr<api::experimental_system_info_cpu::CpuUpdateInfo> info);
 
   // Used to record the event names being watched.
   std::multiset<std::string> watching_event_set_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemInfoEventRouter);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_SYSTEM_INFO_EVENT_ROUTER_H_