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

public/platform/WebDeviceOrientationListener.h

Index: public/platform/WebDeviceOrientationListener.h
diff --git a/public/platform/WebDeviceOrientationListener.h b/public/platform/WebDeviceOrientationListener.h
index 5c88835753d9fde6cbcb7c419fbb5b6233005678..ca95387289d2bdc6b0c28ffc652d1c4756abf15a 100644
--- a/public/platform/WebDeviceOrientationListener.h
+++ b/public/platform/WebDeviceOrientationListener.h
@@ -31,11 +31,13 @@
 #ifndef WebDeviceOrientationListener_h
 #define WebDeviceOrientationListener_h
 
+#include "WebPlatformEventListener.h"
+
 namespace blink {
 
 class WebDeviceOrientationData;
 
-class WebDeviceOrientationListener {
+class WebDeviceOrientationListener : public WebPlatformEventListener {
 public:
     // This method is called every time new device orientation data is available.
     virtual void didChangeDeviceOrientation(const WebDeviceOrientationData&) = 0;