Allow creation of ImageBitmaps from WebGL canvases.

Source/core/page/ImageBitmap.cpp

 // Copyright 2013 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 "config.h"
 #include "core/page/ImageBitmap.h"
 
 #include "core/html/HTMLCanvasElement.h"
 #include "core/html/HTMLImageElement.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/html/ImageData.h"
+#include "core/html/canvas/CanvasRenderingContext.h"
 #include "core/platform/graphics/BitmapImage.h"
 #include "core/platform/graphics/GraphicsContext.h"
 #include "wtf/RefPtr.h"
 
 using namespace std;
 
 namespace WebCore {
 
 static inline IntRect normalizeRect(const IntRect& rect)
 {
@@ skipping 42 matching lines @@
 }
 
 ImageBitmap::ImageBitmap(HTMLCanvasElement* canvas, const IntRect& cropRect)
     : m_cropRect(cropRect)
     , m_imageElement(0)
 {
     IntSize canvasSize = canvas->size();
     IntRect srcRect = intersection(cropRect, IntRect(IntPoint(), canvasSize));
     IntRect dstRect(IntPoint(), srcRect.size());
 
+    CanvasRenderingContext* sourceContext = canvas->renderingContext();
+    if (!sourceContext || !sourceContext->isAccelerated() || !sourceContext->is2d())

[Justin Novosad, 2013/08/19 20:20:51]

Do we really need to call makeRenderingResultsAvailable() in all these cases? 
If it is just needed for WebGL, shouldn't the condition be:
if (sourceContext && !sourceContext->is2d())
If the other conditions are necessary, what use cases do they fix?  Do we have
tests for those use cases?

+        canvas->makeRenderingResultsAvailable();
+
     m_buffer = ImageBuffer::create(canvasSize);
     m_buffer->context()->drawImageBuffer(canvas->buffer(), dstRect, srcRect);
     m_bitmap = m_buffer->copyImage(DontCopyBackingStore);
     m_bitmapRect = IntRect(IntPoint(max(0, -cropRect.x()), max(0, -cropRect.y())), srcRect.size());
 
     ScriptWrappable::init(this);
 }
 
 ImageBitmap::ImageBitmap(ImageData* data, const IntRect& cropRect)
     : m_cropRect(cropRect)
@@ skipping 78 matching lines @@
 
 PassRefPtr<Image> ImageBitmap::bitmapImage() const
 {
     ASSERT((m_imageElement || m_bitmap) && (!m_imageElement || !m_bitmap));
     if (m_imageElement)
         return cropImage(m_imageElement->cachedImage()->image(), m_cropRect);
     return m_bitmap;
 }
 
 }