Revert "Remove MediaStreamDescriptor and call/use WebMediaStream directly"

Source/core/platform/mediastream/RTCStatsRequest.h

Index: Source/core/platform/mediastream/RTCStatsRequest.h
diff --git a/Source/core/platform/mediastream/RTCStatsRequest.h b/Source/core/platform/mediastream/RTCStatsRequest.h
index b59a05cedb7c96b30b7a7dc4b657b84fe111a482..c727f54351971f3c01e60cf4b35eda5600a4be1f 100644
--- a/Source/core/platform/mediastream/RTCStatsRequest.h
+++ b/Source/core/platform/mediastream/RTCStatsRequest.h
@@ -35,13 +35,10 @@
 #include <wtf/RefCounted.h>
 #include <wtf/text/WTFString.h>
 
-namespace WebKit {
-class WebMediaStream;
-}
-
 namespace WebCore {
 
 class MediaStreamComponent;
+class MediaStreamDescriptor;
 class RTCStatsResponseBase;
 
 class RTCStatsRequest : public RefCounted<RTCStatsRequest> {
@@ -50,7 +47,7 @@ public:
 
     virtual PassRefPtr<RTCStatsResponseBase> createResponse() = 0;
     virtual bool hasSelector() = 0;
-    virtual WebKit::WebMediaStream stream() = 0;
+    virtual MediaStreamDescriptor* stream() = 0;
     virtual MediaStreamComponent* component() = 0;
     virtual void requestSucceeded(PassRefPtr<RTCStatsResponseBase>) = 0;