Synchronize OffscreenCanvas content with the placeholder canvas

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 682 matching lines @@
   UseCounter::Feature feature = UseCounter::OffscreenCanvasCommitWebGL;
   UseCounter::count(scriptState->getExecutionContext(), feature);
   if (!getOffscreenCanvas()) {
     exceptionState.throwDOMException(InvalidStateError,
                                      "Commit() was called on a rendering "
                                      "context that was not created from an "
                                      "OffscreenCanvas.");
     return;
   }
   // no HTMLCanvas associated, thrown InvalidStateError
-  if (getOffscreenCanvas()->getAssociatedCanvasId() == -1) {
+  if (!getOffscreenCanvas()->hasPlaceholderCanvas()) {
     exceptionState.throwDOMException(InvalidStateError,
                                      "Commit() was called on a context whose "
                                      "OffscreenCanvas is not associated with a "
                                      "canvas element.");
     return;
   }
   if (!drawingBuffer())
     return;
   double commitStartTime = WTF::monotonicallyIncreasingTime();
   // TODO(crbug.com/646864): Make commit() work correctly with
@@ skipping 6954 matching lines @@
 
 void WebGLRenderingContextBase::getHTMLOrOffscreenCanvas(
     HTMLCanvasElementOrOffscreenCanvas& result) const {
   if (canvas())
     result.setHTMLCanvasElement(canvas());
   else
     result.setOffscreenCanvas(getOffscreenCanvas());
 }
 
 }  // namespace blink