Make OffscreenCanvas resizeable

third_party/WebKit/Source/platform/graphics/OffscreenCanvasPlaceholder.cpp

 // Copyright 2016 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 "platform/graphics/OffscreenCanvasPlaceholder.h"
 
 #include "platform/CrossThreadFunctional.h"
 #include "platform/WebTaskRunner.h"
 #include "platform/graphics/Image.h"
 #include "platform/graphics/OffscreenCanvasFrameDispatcher.h"
@@ skipping 49 matching lines @@
   placeholderRegistry().remove(m_placeholderId);
   m_placeholderId = kNoPlaceholderId;
 }
 
 void OffscreenCanvasPlaceholder::setPlaceholderFrame(
     RefPtr<Image> newFrame,
     WeakPtr<OffscreenCanvasFrameDispatcher> dispatcher,
     std::unique_ptr<WebTaskRunner> taskRunner,
     unsigned resourceId) {
   DCHECK(isPlaceholderRegistered());
+  DCHECK(newFrame);
   releasePlaceholderFrame();
   m_placeholderFrame = std::move(newFrame);
   m_frameDispatcher = std::move(dispatcher);
   m_frameDispatcherTaskRunner = std::move(taskRunner);
   m_placeholderFrameResourceId = resourceId;
+  setSize(m_placeholderFrame->size());
 }
 
 void OffscreenCanvasPlaceholder::releasePlaceholderFrame() {
   DCHECK(isPlaceholderRegistered());
   if (m_placeholderFrame) {
     m_placeholderFrame->transfer();
     m_frameDispatcherTaskRunner->postTask(
         BLINK_FROM_HERE,
         crossThreadBind(releaseFrameToDispatcher, std::move(m_frameDispatcher),
                         std::move(m_placeholderFrame),
                         m_placeholderFrameResourceId));
   }
 }
 
 }  // blink