Revert of Remove MediaStreamTrack.getSources().

third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp

Index: third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp
diff --git a/third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp b/third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp
index 0e4d5d1bcbbe7e34daaa156646d2de57a5faa3d2..9739d9229852dec285f5463dd93da55fea0f49e7 100644
--- a/third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp
+++ b/third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp
@@ -33,11 +33,14 @@
 #include "core/frame/Deprecation.h"
 #include "modules/mediastream/MediaConstraintsImpl.h"
 #include "modules/mediastream/MediaStream.h"
+#include "modules/mediastream/MediaStreamTrackSourcesCallback.h"
+#include "modules/mediastream/MediaStreamTrackSourcesRequestImpl.h"
 #include "modules/mediastream/MediaTrackSettings.h"
 #include "modules/mediastream/UserMediaController.h"
 #include "platform/mediastream/MediaStreamCenter.h"
 #include "platform/mediastream/MediaStreamComponent.h"
 #include "public/platform/WebMediaStreamTrack.h"
+#include "public/platform/WebSourceInfo.h"
 #include "wtf/Assertions.h"
 #include <memory>
 
@@ -126,6 +129,24 @@
 
   NOTREACHED();
   return String();
+}
+
+void MediaStreamTrack::getSources(ExecutionContext* context,
+                                  MediaStreamTrackSourcesCallback* callback,
+                                  ExceptionState& exceptionState) {
+  LocalFrame* frame = toDocument(context)->frame();
+  UserMediaController* userMedia = UserMediaController::from(frame);
+  if (!userMedia) {
+    exceptionState.throwDOMException(
+        NotSupportedError,
+        "No sources controller available; is this a detached window?");
+    return;
+  }
+  Deprecation::countDeprecation(context,
+                                UseCounter::MediaStreamTrackGetSources);
+  MediaStreamTrackSourcesRequest* request =
+      MediaStreamTrackSourcesRequestImpl::create(*context, callback);
+  userMedia->requestSources(request);
 }
 
 void MediaStreamTrack::stopTrack(ExceptionState& exceptionState) {