2D canvas: remain in deferred rendering mode with canvas to canvas drawImage

Source/platform/graphics/ImageBuffer.cpp

 /*
  * Copyright (c) 2008, Google Inc. All rights reserved.
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
@@ skipping 131 matching lines @@
 }
 
 void ImageBuffer::resetCanvas(SkCanvas* canvas) const
 {
     if (m_client)
         m_client->restoreCanvasMatrixClipStack(canvas);
 }
 
 PassRefPtr<SkImage> ImageBuffer::newSkImageSnapshot() const
 {
+    if (m_animationState == InitialAnimationState)
+        m_animationState = DidAcquireSnapshot;

[Stephen White, 2015/08/17 15:15:07]

Naming nit: m_drawnToAfterSnapshot or something like that?

+
     if (!isSurfaceValid())
         return nullptr;
     return m_surface->newImageSnapshot();
 }
 
 PassRefPtr<Image> ImageBuffer::newImageSnapshot() const
 {
-    if (!isSurfaceValid())
-        return nullptr;
-    RefPtr<SkImage> snapshot = m_surface->newImageSnapshot();
+    RefPtr<SkImage> snapshot = newSkImageSnapshot();
     if (!snapshot)
         return nullptr;
     return StaticBitmapImage::create(snapshot);
 }
 
+void ImageBuffer::didDraw(const FloatRect& rect) const
+{
+    if (m_animationState == DidAcquireSnapshot)
+        m_animationState = DidDrawAfterSnapshot;
+    m_surface->didDraw(rect);
+}
+
 WebLayer* ImageBuffer::platformLayer() const
 {
     return m_surface->layer();
 }
 
 bool ImageBuffer::copyToPlatformTexture(WebGraphicsContext3D* context, Platform3DObject texture, GLenum internalFormat, GLenum destType, GLint level, bool premultiplyAlpha, bool flipY)
 {
     if (!m_surface->isAccelerated() || !isSurfaceValid())
         return false;
 
@@ skipping 185 matching lines @@
     ASSERT(MIMETypeRegistry::isSupportedImageMIMETypeForEncoding(mimeType));
 
     Vector<char> encodedImage;
     if (!encodeImage(*this, mimeType, quality, &encodedImage))
         return "data:,";
 
     return "data:" + mimeType + ";base64," + base64Encode(encodedImage);
 }
 
 } // namespace blink