Remove unused ExtraData support on exported mediastream objects.

Source/platform/mediastream/RTCSessionDescriptionRequest.h

Index: Source/platform/mediastream/RTCSessionDescriptionRequest.h
diff --git a/Source/platform/mediastream/RTCSessionDescriptionRequest.h b/Source/platform/mediastream/RTCSessionDescriptionRequest.h
index 467e47de62aef65f98b4fd2ce96f93121700e17f..37a50ebe1863b0f8d10cb8b0a9ee00ce6cd9749e 100644
--- a/Source/platform/mediastream/RTCSessionDescriptionRequest.h
+++ b/Source/platform/mediastream/RTCSessionDescriptionRequest.h
@@ -32,36 +32,22 @@
 #define RTCSessionDescriptionRequest_h
 
 #include "platform/heap/Handle.h"
-#include "wtf/PassOwnPtr.h"
-#include "wtf/text/WTFString.h"
+#include "wtf/Forward.h"
 
 namespace blink {
 class WebRTCSessionDescription;
 
 class RTCSessionDescriptionRequest : public GarbageCollectedFinalized<RTCSessionDescriptionRequest> {
 public:
-    class ExtraData {
-    public:
-        virtual ~ExtraData() { }
-    };
-
     virtual ~RTCSessionDescriptionRequest() { }
 
     virtual void requestSucceeded(const WebRTCSessionDescription&) = 0;
     virtual void requestFailed(const String& error) = 0;
 
-    ExtraData* extraData() const { return m_extraData.get(); }
-    void setExtraData(PassOwnPtr<ExtraData> extraData) { m_extraData = extraData; }
-
-    // Need to eagerly finalize ExtraData.
-    EAGERLY_FINALIZE();
     DEFINE_INLINE_VIRTUAL_TRACE() { }
 
 protected:
     RTCSessionDescriptionRequest() { }
-
-private:
-    OwnPtr<ExtraData> m_extraData;
 };
 
 } // namespace blink