Add the basic code skeleton for system info event router

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 "base/memory/scoped_ptr.h"
+#include "base/memory/singleton.h"
+#include "base/values.h"
+#include "chrome/browser/extensions/system_info_watcher.h"
+#include "chrome/browser/profiles/profile.h"
+
+namespace extensions {
+
+class SystemInfoWatcher;
+
+// Event router for systemInfo API. It is a singleton instance shared by
+// multiple profiles.
+class SystemInfoEventRouter : public SystemInfoWatcher::Observer {
+ public:
+  // The single instance of the event router.
+  static SystemInfoEventRouter* GetInstance();
+
+  // Add/remove event listener for the |event_name| event from |profile|.
+  void AddEventListener(Profile* profile, const std::string& event_name);
+  void RemoveEventListener(Profile* profile, const std::string& event_name);
+
+  // Return true if the |event_name| event is already being listened.
+  bool HasEventListener(const std::string& event_name);
+
+ private:
+  friend struct DefaultSingletonTraits<SystemInfoEventRouter>;
+
+  // Map of the profile and its events that are being listened.
+  typedef std::map<Profile*, std::set<std::string> > EventListenerMap;
+
+  SystemInfoEventRouter();
+  virtual ~SystemInfoEventRouter();
+
+  // SystemInfoWatcher::Observer overridens.
+  void OnStorageDeviceAvailableCapacityChanged(const std::string& id,
+                                               double available_capacity);
+  void OnStorageDeviceAdded(const std::string& id,
+                            const std::string& type,
+                            double capacity,
+                            double available_capacity);
+  void OnStorageDeviceRemoved(const std::string& id);
+
+
+  // Dispatch systemInfo event to all profiles it observes.
+  void DispatchEvent(const std::string& event_name,
+                     scoped_ptr<base::ListValue> args);
+
+  // The watcher for system information changes.
+  SystemInfoWatcher* system_info_watcher_;
+
+  EventListenerMap event_listener_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(SystemInfoEventRouter);
+};
+
+}  // namespace extensions
+#endif  // CHROME_BROWSER_EXTENSIONS_SYSTEM_INFO_EVENT_ROUTER_H_