Reduce repetitive EventTarget subclassing

Source/modules/mediastream/RTCDataChannel.h

Index: Source/modules/mediastream/RTCDataChannel.h
diff --git a/Source/modules/mediastream/RTCDataChannel.h b/Source/modules/mediastream/RTCDataChannel.h
index d85a544a3b4e3a96ffbea69795885f0270a3fe3c..b725491893b64b1c530c682ebc2740a5a7483ee0 100644
--- a/Source/modules/mediastream/RTCDataChannel.h
+++ b/Source/modules/mediastream/RTCDataChannel.h
@@ -42,7 +42,7 @@ class ExceptionState;
 class RTCDataChannelHandler;
 class RTCPeerConnectionHandler;
 
-class RTCDataChannel : public RefCounted<RTCDataChannel>, public ScriptWrappable, public EventTarget, public RTCDataChannelHandlerClient {
+class RTCDataChannel : public RefCounted<RTCDataChannel>, public ScriptWrappable, public EventTargetWithInlineData, public RTCDataChannelHandlerClient {
 public:
     static PassRefPtr<RTCDataChannel> create(ScriptExecutionContext*, PassOwnPtr<RTCDataChannelHandler>);
     static PassRefPtr<RTCDataChannel> create(ScriptExecutionContext*, RTCPeerConnectionHandler*, const String& label, const WebKit::WebRTCDataChannelInit&, ExceptionState&);
@@ -93,11 +93,8 @@ private:
     void scheduledEventTimerFired(Timer<RTCDataChannel>*);
 
     // EventTarget
-    virtual EventTargetData* eventTargetData();
-    virtual EventTargetData* ensureEventTargetData();
-    virtual void refEventTarget() { ref(); }
-    virtual void derefEventTarget() { deref(); }
-    EventTargetData m_eventTargetData;
+    virtual void refEventTarget() OVERRIDE { ref(); }
+    virtual void derefEventTarget() OVERRIDE { deref(); }
     ScriptExecutionContext* m_scriptExecutionContext;
 
     // RTCDataChannelHandlerClient