Refactor ImageBuffer to make OffscreenCanvas match HTMLCanvasElement

third_party/WebKit/Source/core/editing/Editor.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  *
  * 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
@@ skipping 552 matching lines @@
 static PassRefPtr<Image> ImageFromNode(const Node& node) {
   DCHECK(!node.GetDocument().NeedsLayoutTreeUpdate());
   DocumentLifecycle::DisallowTransitionScope disallow_transition(
       node.GetDocument().Lifecycle());
 
   LayoutObject* layout_object = node.GetLayoutObject();
   if (!layout_object)
     return nullptr;
 
   if (layout_object->IsCanvas()) {
-    return toHTMLCanvasElement(node).CopiedImage(
-        kFrontBuffer, kPreferNoAcceleration, kSnapshotReasonCopyToClipboard);
+    return toHTMLCanvasElement(const_cast<Node&>(node))
+        .CopiedImage(kFrontBuffer, kPreferNoAcceleration,
+                     kSnapshotReasonCopyToClipboard);
   }
 
   if (layout_object->IsImage()) {
     LayoutImage* layout_image = ToLayoutImage(layout_object);
     if (!layout_image)
       return nullptr;
 
     ImageResourceContent* cached_image = layout_image->CachedImage();
     if (!cached_image || cached_image->ErrorOccurred())
       return nullptr;
@@ skipping 1233 matching lines @@
 
 DEFINE_TRACE(Editor) {
   visitor->Trace(frame_);
   visitor->Trace(last_edit_command_);
   visitor->Trace(undo_stack_);
   visitor->Trace(mark_);
   visitor->Trace(typing_style_);
 }
 
 }  // namespace blink