Make IDL Callbacks non-refcounted by default

Source/modules/mediastream/MediaStreamTrackSourcesCallback.h

Index: Source/modules/mediastream/MediaStreamTrackSourcesCallback.h
diff --git a/Source/modules/mediastream/MediaStreamTrackSourcesCallback.h b/Source/modules/mediastream/MediaStreamTrackSourcesCallback.h
index d58afeb15455d5adffa2500c1fe6fc7a1dce73b8..ddce2c495209ad07fe2929ab3c39e9600fc273c8 100644
--- a/Source/modules/mediastream/MediaStreamTrackSourcesCallback.h
+++ b/Source/modules/mediastream/MediaStreamTrackSourcesCallback.h
@@ -27,13 +27,11 @@
 #define MediaStreamTrackSourcesCallback_h
 
 #include "modules/mediastream/SourceInfo.h"
-#include "wtf/RefCounted.h"
-
 namespace WebCore {
 
 class MediaStreamTrackSourcesResponse;
 
-class MediaStreamTrackSourcesCallback : public RefCounted<MediaStreamTrackSourcesCallback> {
+class MediaStreamTrackSourcesCallback {
 public:
     virtual ~MediaStreamTrackSourcesCallback() { }
     virtual bool handleEvent(const SourceInfoVector&) = 0;