Add task location information to ExecutionContext

Source/modules/mediastream/MediaStreamTrackSourcesRequestImpl.cpp

Index: Source/modules/mediastream/MediaStreamTrackSourcesRequestImpl.cpp
diff --git a/Source/modules/mediastream/MediaStreamTrackSourcesRequestImpl.cpp b/Source/modules/mediastream/MediaStreamTrackSourcesRequestImpl.cpp
index 76e6294e3a2410ff4c1a591e0085f7833a489260..b5e98000bf01c53a31ac894e1779f73137660420 100644
--- a/Source/modules/mediastream/MediaStreamTrackSourcesRequestImpl.cpp
+++ b/Source/modules/mediastream/MediaStreamTrackSourcesRequestImpl.cpp
@@ -31,6 +31,7 @@
 #include "modules/mediastream/MediaStreamTrackSourcesCallback.h"
 #include "platform/weborigin/SecurityOrigin.h"
 #include "public/platform/WebSourceInfo.h"
+#include "public/platform/WebTraceLocation.h"
 #include "wtf/Functional.h"
 #include "wtf/PassOwnPtr.h"
 
@@ -62,7 +63,7 @@ void MediaStreamTrackSourcesRequestImpl::requestSucceeded(const WebVector<WebSou
 
     for (size_t i = 0; i < webSourceInfos.size(); ++i)
         m_sourceInfos.append(SourceInfo::create(webSourceInfos[i]));
-    m_executionContext->postTask(createCrossThreadTask(&MediaStreamTrackSourcesRequestImpl::performCallback, this));
+    m_executionContext->postTask(FROM_HERE, createCrossThreadTask(&MediaStreamTrackSourcesRequestImpl::performCallback, this));
 }
 
 void MediaStreamTrackSourcesRequestImpl::performCallback()