Decouple Canvas from DisplayList and map Picture and PictureRecorder more directly to their Skia co…

sky/engine/core/painting/LayoutRoot.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 "sky/engine/config.h"
 #include "sky/engine/core/painting/LayoutRoot.h"
 
 #include "sky/engine/core/dom/Document.h"
 #include "sky/engine/core/dom/Element.h"
 #include "sky/engine/core/frame/FrameView.h"
 #include "sky/engine/core/frame/LocalFrame.h"
 #include "sky/engine/core/frame/Settings.h"
+#include "sky/engine/core/painting/Canvas.h"
 #include "sky/engine/core/painting/PaintingTasks.h"
 #include "sky/engine/platform/geometry/IntRect.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 
 namespace blink {
 
 PassRefPtr<LayoutRoot> LayoutRoot::create()
 {
     return adoptRef(new LayoutRoot);
 }
@@ skipping 53 matching lines @@
     m_frame->view()->setLayoutSize(maxSize);
 
     m_document->updateLayout();
 
     m_document->setFrame(nullptr);
     m_frame->setDocument(nullptr);
 }
 
 void LayoutRoot::paint(Canvas* canvas)
 {
-    if (m_document)
+    if (m_document && canvas && canvas->skCanvas())
         rootElement()->paint(canvas);
 }
 
 } // namespace blink