Fix clone() behavior on CanvasCaptureMediaStreamTrack

third_party/WebKit/Source/modules/mediacapturefromelement/CanvasCaptureMediaStreamTrack.cpp

Index: third_party/WebKit/Source/modules/mediacapturefromelement/CanvasCaptureMediaStreamTrack.cpp
diff --git a/third_party/WebKit/Source/modules/mediacapturefromelement/CanvasCaptureMediaStreamTrack.cpp b/third_party/WebKit/Source/modules/mediacapturefromelement/CanvasCaptureMediaStreamTrack.cpp
index 736e41d45487525427e897f4f9ad5925b317f3f0..a8a12892e584146fc2c1a7917173909d933991e4 100644
--- a/third_party/WebKit/Source/modules/mediacapturefromelement/CanvasCaptureMediaStreamTrack.cpp
+++ b/third_party/WebKit/Source/modules/mediacapturefromelement/CanvasCaptureMediaStreamTrack.cpp
@@ -8,6 +8,7 @@
 #include "core/html/HTMLCanvasElement.h"
 #include "modules/mediacapturefromelement/AutoCanvasDrawListener.h"
 #include "platform/NotImplemented.h"
+#include "platform/mediastream/MediaStreamCenter.h"
 
 namespace blink {
 
@@ -27,6 +28,14 @@ void CanvasCaptureMediaStreamTrack::requestFrame()
     return;
 }
 
+CanvasCaptureMediaStreamTrack* CanvasCaptureMediaStreamTrack::clone(ExecutionContext* context)
+{
+    MediaStreamComponent* clonedComponent = MediaStreamComponent::create(component()->source());
+    CanvasCaptureMediaStreamTrack* clonedTrack = new CanvasCaptureMediaStreamTrack(*this, clonedComponent);
+    MediaStreamCenter::instance().didCreateMediaStreamTrack(clonedComponent);
+    return clonedTrack;
+}
+
 DEFINE_TRACE(CanvasCaptureMediaStreamTrack)
 {
     visitor->trace(m_canvasElement);
@@ -34,6 +43,15 @@ DEFINE_TRACE(CanvasCaptureMediaStreamTrack)
     MediaStreamTrack::trace(visitor);
 }
 
+CanvasCaptureMediaStreamTrack::CanvasCaptureMediaStreamTrack(const CanvasCaptureMediaStreamTrack& track, MediaStreamComponent* component)
+    :MediaStreamTrack(track.m_canvasElement->executionContext(), component)
+    , m_canvasElement(track.m_canvasElement)
+    , m_drawListener(track.m_drawListener)
+{
+    suspendIfNeeded();
+    m_canvasElement->addListener(m_drawListener.get());
+}
+
 CanvasCaptureMediaStreamTrack::CanvasCaptureMediaStreamTrack(MediaStreamComponent* component, PassRefPtrWillBeRawPtr<HTMLCanvasElement> element, const PassOwnPtr<WebCanvasCaptureHandler> handler)
     : MediaStreamTrack(element->executionContext(), component)
     , m_canvasElement(element)