Introduce PlatformEvent to handle Device events, Battery events and Gamepad events.

Source/modules/gamepad/GamepadDispatcher.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 GamepadDispatcher_h
 #define GamepadDispatcher_h
 
-#include "core/frame/DeviceEventDispatcherBase.h"
+#include "core/frame/PlatformEventDispatcher.h"
 #include "platform/heap/Handle.h"
 #include "public/platform/WebGamepad.h"
 #include "public/platform/WebGamepadListener.h"
 
 namespace blink {
 class WebGamepads;
 }
 
 namespace blink {
 
 class NavigatorGamepad;
 
-class GamepadDispatcher : public DeviceEventDispatcherBase, public blink::WebGamepadListener {
+class GamepadDispatcher : public PlatformEventDispatcher, public blink::WebGamepadListener {
 public:
     static GamepadDispatcher& instance();
 
     void sampleGamepads(blink::WebGamepads&);
 
     struct ConnectionChange {
         blink::WebGamepad pad;
         unsigned index;
     };
 
     const ConnectionChange& latestConnectionChange() const { return m_latestChange; }
 
 private:
     GamepadDispatcher();
     virtual ~GamepadDispatcher();
 
     // WebGamepadListener
     virtual void didConnectGamepad(unsigned index, const blink::WebGamepad&) OVERRIDE;
     virtual void didDisconnectGamepad(unsigned index, const blink::WebGamepad&) OVERRIDE;
 
-    // DeviceEventDispatcherBase
+    // PlatformEventDispatcher
     virtual void startListening() OVERRIDE;
     virtual void stopListening() OVERRIDE;
 
     void dispatchDidConnectOrDisconnectGamepad(unsigned index, const blink::WebGamepad&, bool connected);
 
     ConnectionChange m_latestChange;
 };
 
 } // namespace blink
 
 #endif