Use SkImage snapshots for ImageBufferSurface texture access

Source/platform/graphics/gpu/AcceleratedImageBufferSurface.cpp

 /*
  * Copyright (c) 2013, Google Inc. 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
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 44 matching lines @@
     SkAlphaType alphaType = (Opaque == opacityMode) ? kOpaque_SkAlphaType : kPremul_SkAlphaType;
     SkImageInfo info = SkImageInfo::MakeN32(size.width(), size.height(), alphaType);
     SkSurfaceProps disableLCDProps(0, kUnknown_SkPixelGeometry);
     m_surface = adoptPtr(SkSurface::NewRenderTarget(grContext, SkSurface::kYes_Budgeted, info, 0 /* sampleCount */,
         Opaque == opacityMode ? nullptr : &disableLCDProps));
     if (!m_surface.get())
         return;
     clear();
 }
 
-Platform3DObject AcceleratedImageBufferSurface::getBackingTexture() const
+// This is a duplicate of newImageSnapshot(), but we need different entry points to
+// support Canvas2DLayerBridge's slightly divergent semantics.

[reed1, 2015/06/23 14:38:09]

Lets document somewhere what those slightly divergent semantics are!

+PassRefPtr<SkImage> AcceleratedImageBufferSurface::getBackingTextureImage() const
 {
-    // Before returning the texture, all drawing operations must be completed.
-    m_surface->getCanvas()->flush();
-    GrRenderTarget* renderTarget = m_surface->getCanvas()->getTopDevice()->accessRenderTarget();
-    if (renderTarget) {
-        return renderTarget->asTexture()->getTextureHandle();
-    }
-    return 0;
+    return adoptRef(m_surface->newImageSnapshot());
 }
 
 void AcceleratedImageBufferSurface::didModifyBackingTexture()
 {
     m_surface->getCanvas()->getTopDevice()->accessBitmap(false).notifyPixelsChanged();
 }
 
 PassRefPtr<SkImage> AcceleratedImageBufferSurface::newImageSnapshot() const
 {
     return adoptRef(m_surface->newImageSnapshot());
 }
 
 } // namespace blink