Synchronize OffscreenCanvas content with the placeholder canvas

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/offscreencanvas/OffscreenCanvas.h"
 
 #include "core/dom/ExceptionCode.h"
 #include "core/fileapi/Blob.h"
 #include "core/html/ImageData.h"
 #include "core/html/canvas/CanvasAsyncBlobCreator.h"
@@ skipping 14 matching lines @@
     : m_size(size), m_originClean(true) {}
 
 OffscreenCanvas* OffscreenCanvas::create(unsigned width, unsigned height) {
   return new OffscreenCanvas(
       IntSize(clampTo<int>(width), clampTo<int>(height)));
 }
 
 void OffscreenCanvas::setWidth(unsigned width, ExceptionState& exceptionState) {
   // If this OffscreenCanvas is transferred control by an html canvas,
   // its size is determined by html canvas's size and cannot be resized.
-  if (m_canvasId >= 0) {
+  if (hasPlaceholderCanvas()) {
     exceptionState.throwDOMException(InvalidStateError,
                                      "Resizing is not allowed on an "
                                      "OffscreenCanvas that has been "
                                      "transferred control from a canvas.");
     return;
   }
   m_size.setWidth(clampTo<int>(width));
 }
 
 void OffscreenCanvas::setHeight(unsigned height,
                                 ExceptionState& exceptionState) {
   // Same comment as above.
-  if (m_canvasId >= 0) {
+  if (hasPlaceholderCanvas()) {
     exceptionState.throwDOMException(InvalidStateError,
                                      "Resizing is not allowed on an "
                                      "OffscreenCanvas that has been "
                                      "transferred control from a canvas.");
     return;
   }
   m_size.setHeight(clampTo<int>(height));
 }
 
 void OffscreenCanvas::setNeutered() {
@@ skipping 118 matching lines @@
 bool OffscreenCanvas::isAccelerated() const {
   return m_context && m_context->isAccelerated();
 }
 
 OffscreenCanvasFrameDispatcher* OffscreenCanvas::getOrCreateFrameDispatcher() {
   if (!m_frameDispatcher) {
     // 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.
     m_frameDispatcher = wrapUnique(new OffscreenCanvasFrameDispatcherImpl(
-        m_clientId, m_sinkId, m_localId, m_nonceHigh, m_nonceLow, width(),
-        height()));
+        m_clientId, m_sinkId, m_localId, m_nonceHigh, m_nonceLow,
+        m_placeholderCanvasId, width(), height()));
   }
   return m_frameDispatcher.get();
 }
 
 ScriptPromise OffscreenCanvas::convertToBlob(ScriptState* scriptState,
                                              const ImageEncodeOptions& options,
                                              ExceptionState& exceptionState) {
   if (this->isNeutered()) {
     exceptionState.throwDOMException(InvalidStateError,
                                      "OffscreenCanvas object is detached.");
@@ skipping 36 matching lines @@
   asyncCreator->scheduleAsyncBlobCreation(options.quality());
 
   return resolver->promise();
 }
 
 DEFINE_TRACE(OffscreenCanvas) {
   visitor->trace(m_context);
 }
 
 }  // namespace blink