Make Screen Orientation use Platform Events in order to handle polling.

public/platform/Platform.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 603 matching lines @@
             break;
         case blink::WebPlatformEventDeviceLight:
             setDeviceLightListener(static_cast<blink::WebDeviceLightListener*>(listener));
             break;
         case blink::WebPlatformEventBattery:
             setBatteryStatusListener(static_cast<blink::WebBatteryStatusListener*>(listener));
             break;
         case blink::WebPlatformEventGamepad:
             setGamepadListener(static_cast<blink::WebGamepadListener*>(listener));
             break;
+        case blink::WebPlatformEventScreenOrientation:
+            // No backward-compatibility support here.
+            break;
         }
     }
 
     // Request the platform to stop listening to the specified event and no
     // longer notify the listener, if any.
     virtual void stopListening(blink::WebPlatformEventType type)
     {
         // FIXME: this implementation is only there for backward compatibility.
         // It should be removed when the content layer will implement this method.
         switch (type) {
         case blink::WebPlatformEventDeviceMotion:
             setDeviceMotionListener(0);
             break;
         case blink::WebPlatformEventDeviceOrientation:
             setDeviceOrientationListener(0);
             break;
         case blink::WebPlatformEventDeviceLight:
             setDeviceLightListener(0);
             break;
         case blink::WebPlatformEventBattery:
             setBatteryStatusListener(0);
             break;
         case blink::WebPlatformEventGamepad:
             setGamepadListener(0);
             break;
+        case blink::WebPlatformEventScreenOrientation:
+            // No backward-compatibility support here.
+            break;
         }
     }
 
     // Deprecated: remove when content/ is updated.
     virtual void setDeviceMotionListener(blink::WebDeviceMotionListener*) { }
     virtual void setDeviceOrientationListener(blink::WebDeviceOrientationListener*) { }
     virtual void setDeviceLightListener(blink::WebDeviceLightListener*) { }
     virtual void setBatteryStatusListener(blink::WebBatteryStatusListener*) { }
     virtual void setGamepadListener(blink::WebGamepadListener*) { }
 
@@ skipping 21 matching lines @@
     virtual WebNotificationPresenter* notificationPresenter() { return 0; }
 
 
 protected:
     virtual ~Platform() { }
 };
 
 } // namespace blink
 
 #endif