Revert "Remove MediaStreamDescriptor and call/use WebMediaStream directly"

Source/modules/mediastream/RTCStatsRequestImpl.cpp

Index: Source/modules/mediastream/RTCStatsRequestImpl.cpp
diff --git a/Source/modules/mediastream/RTCStatsRequestImpl.cpp b/Source/modules/mediastream/RTCStatsRequestImpl.cpp
index a19413992d4020db6f6491e0f6e1fcd76e387865..0ad09be778844435c359e10edfb27df810a42c40 100644
--- a/Source/modules/mediastream/RTCStatsRequestImpl.cpp
+++ b/Source/modules/mediastream/RTCStatsRequestImpl.cpp
@@ -26,7 +26,6 @@
 
 #include "modules/mediastream/RTCStatsRequestImpl.h"
 
-#include "core/platform/mediastream/MediaStreamComponent.h"
 #include "core/platform/mediastream/RTCStatsRequest.h"
 #include "modules/mediastream/MediaStreamTrack.h"
 #include "modules/mediastream/RTCStatsCallback.h"
@@ -44,10 +43,9 @@ PassRefPtr<RTCStatsRequestImpl> RTCStatsRequestImpl::create(ScriptExecutionConte
 RTCStatsRequestImpl::RTCStatsRequestImpl(ScriptExecutionContext* context, PassRefPtr<RTCStatsCallback> callback, PassRefPtr<MediaStreamTrack> selector)
     : ActiveDOMObject(context)
     , m_successCallback(callback)
+    , m_stream(selector ? selector->component()->stream() : 0)
     , m_component(selector ? selector->component() : 0)
 {
-    if (selector)
-        m_webStream = selector->component()->stream();
 }
 
 RTCStatsRequestImpl::~RTCStatsRequestImpl()
@@ -61,12 +59,12 @@ PassRefPtr<RTCStatsResponseBase> RTCStatsRequestImpl::createResponse()
 
 bool RTCStatsRequestImpl::hasSelector()
 {
-    return !(m_webStream.isNull());
+    return m_stream;
 }
 
-WebKit::WebMediaStream RTCStatsRequestImpl::stream()
+MediaStreamDescriptor* RTCStatsRequestImpl::stream()
 {
-    return m_webStream;
+    return m_stream.get();
 }
 
 MediaStreamComponent* RTCStatsRequestImpl::component()