Use SkImage snapshots for ImageBufferSurface texture access

Source/platform/graphics/Canvas2DLayerBridge.cpp

 /*
  * Copyright (C) 2012 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 495 matching lines @@
     Canvas2DLayerManager::get().layerDidDraw(this);
 }
 
 void Canvas2DLayerBridge::finalizeFrame(const FloatRect &dirtyRect)
 {
     ASSERT(!m_destructionInProgress);
     m_layer->layer()->invalidateRect(enclosingIntRect(dirtyRect));
     m_didRecordDrawCommand = true;
 }
 
-Platform3DObject Canvas2DLayerBridge::getBackingTexture()
+PassRefPtr<SkImage> Canvas2DLayerBridge::getBackingTextureImage()
 {
-    ASSERT(!m_destructionInProgress);
     if (!checkSurfaceValid())

[f(malita), 2015/06/18 16:33:00]

This is the only place where getBackingTextureImage and newImageSnapshot (below)
diverge - all other implementations are identical.

It would be nice to unify them, but I'm not familiar with this code so not sure
what the implications of adding the check & flush to newImageSnapshot() are.

[Justin Novosad, 2015/06/22 18:22:03]

The check is necessary here, and does not make sense elsewhere. It is so 2D
canvas can handle GPU context losses

-        return 0;
-    m_canvas->flush();
+        return nullptr;
+
     context()->flush();
-    GrRenderTarget* renderTarget = m_canvas->getDevice()->accessRenderTarget();
-    if (renderTarget) {
-        return renderTarget->asTexture()->getTextureHandle();
-    }
-    return 0;
+
+    return adoptRef(m_canvas->newImageSnapshot());
 }
 
 PassRefPtr<SkImage> Canvas2DLayerBridge::newImageSnapshot()
 {
     return adoptRef(m_canvas->newImageSnapshot());
 }
 
 Canvas2DLayerBridge::MailboxInfo::MailboxInfo(const MailboxInfo& other) {
     memcpy(&m_mailbox, &other.m_mailbox, sizeof(m_mailbox));
     m_image = other.m_image;
     m_parentLayerBridge = other.m_parentLayerBridge;
 }
 
 } // namespace blink