Cancel GPU acceleration for 2D canvas when drawing very large images

third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h

 // 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.
 
 #ifndef OffscreenCanvas_h
 #define OffscreenCanvas_h
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/ScriptWrappable.h"
@@ skipping 51 matching lines @@
     uint32_t clientId() const { return m_clientId; }
     uint32_t localId() const { return m_localId; }
     uint64_t nonce() const { return m_nonce; }
 
     // CanvasImageSource implementation
     PassRefPtr<Image> getSourceImageForCanvas(SourceImageStatus*, AccelerationHint, SnapshotReason, const FloatSize&) const final;
     bool wouldTaintOrigin(SecurityOrigin*) const final { return !m_originClean; }
     bool isOffscreenCanvas() const final { return true; }
     FloatSize elementSize(const FloatSize& defaultObjectSize) const final { return FloatSize(width(), height()); }
     bool isOpaque() const final;
+    bool isAccelerated() const final;
     int sourceWidth() final { return width(); }
     int sourceHeight() final { return height(); }
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     explicit OffscreenCanvas(const IntSize&);
 
     using ContextFactoryVector = Vector<std::unique_ptr<CanvasRenderingContextFactory>>;
     static ContextFactoryVector& renderingContextFactories();
@@ skipping 15 matching lines @@
     // If this object is not created via HTMLCanvasElement.transferControlToOffscreen(),
     // then the following members would remain as initialized zero values.
     uint32_t m_clientId = 0;
     uint32_t m_localId = 0;
     uint64_t m_nonce = 0;
 };
 
 } // namespace blink
 
 #endif // OffscreenCanvas_h