Create manager to track OffscreenCanvasSurfaceImpl instances

third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp

Index: third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp
diff --git a/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp b/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp
index dd349c5992f4626c9653f1820fb09b272c0ed875..4dc73af46a541ad748ed8a1e98d8f8d56b737bfc 100644
--- a/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp
+++ b/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp
@@ -183,8 +183,10 @@ OffscreenCanvasFrameDispatcher* OffscreenCanvas::getOrCreateFrameDispatcher() {
     // The frame dispatcher connects the current thread of OffscreenCanvas
     // (either main or worker) to the browser process and remains unchanged
     // throughout the lifetime of this OffscreenCanvas.
+    DCHECK_NE(m_canvasId, -1);
     m_frameDispatcher = wrapUnique(new OffscreenCanvasFrameDispatcherImpl(
-        m_clientId, m_sinkId, m_localId, m_nonce, width(), height()));
+        m_canvasId, m_clientId, m_sinkId, m_localId, m_nonce, width(),
+        height()));
   }
   return m_frameDispatcher.get();
 }