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

Source/modules/device_light/DeviceLightDispatcher.h

Index: Source/modules/device_light/DeviceLightDispatcher.h
diff --git a/Source/modules/device_light/DeviceLightDispatcher.h b/Source/modules/device_light/DeviceLightDispatcher.h
index eb35607234e1ce5ecb70f7f69b50dd4b1b7ca012..7c3a8d186b3cb9d9b48bc18fabcf0b93be0bec2a 100644
--- a/Source/modules/device_light/DeviceLightDispatcher.h
+++ b/Source/modules/device_light/DeviceLightDispatcher.h
@@ -5,7 +5,7 @@
 #ifndef DeviceLightDispatcher_h
 #define DeviceLightDispatcher_h
 
-#include "core/frame/DeviceEventDispatcherBase.h"
+#include "core/frame/PlatformEventDispatcher.h"
 #include "public/platform/WebDeviceLightListener.h"
 #include "wtf/RefPtr.h"
 
@@ -14,7 +14,7 @@ namespace blink {
 class DeviceLightController;
 
 // This class listens to device light data and notifies all registered controllers.
-class DeviceLightDispatcher FINAL : public DeviceEventDispatcherBase, public blink::WebDeviceLightListener {
+class DeviceLightDispatcher FINAL : public PlatformEventDispatcher, public blink::WebDeviceLightListener {
 public:
     static DeviceLightDispatcher& instance();
 
@@ -27,7 +27,7 @@ private:
     DeviceLightDispatcher();
     virtual ~DeviceLightDispatcher();
 
-    // Inherited from DeviceEventDispatcherBase.
+    // Inherited from PlatformEventDispatcher.
     virtual void startListening() OVERRIDE;
     virtual void stopListening() OVERRIDE;