Blink API to allow mailbox usage with texture layers for WebGL and Canvas2D.

Source/Platform/chromium/public/WebExternalTextureLayer.h

 /*
  * Copyright (C) 2011 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 28 matching lines @@
 // The texture will be used by the WebLayerTreeView during compositing passes.
 // When in single-thread mode, this means during WebLayerTreeView::composite().
 // When using the threaded compositor, this can mean at an arbitrary time until
 // the WebLayerTreeView is destroyed.
 class WebExternalTextureLayer {
 public:
     virtual ~WebExternalTextureLayer() { }
 
     virtual WebLayer* layer() = 0;
 
+    // Clears texture from the layer.
+    virtual void clearTexture() { }

[piman, 2013/04/08 19:31:31]

What does this mean exactly in terms of cc/ ?
Do you have the CL what implements this on the chromium side?

[alexst (slow to review), 2013/04/08 19:38:01]

Yes, it's below. Basically the equivalent of layer->setTexture(0).

https://codereview.chromium.org/12374028/diff/40001/webkit/compositor_binding...

+
     // Sets the texture id that represents the layer, in the namespace of the
     // compositor context.
     virtual void setTextureId(unsigned) = 0;
 
     // Sets whether or not the texture should be flipped in the Y direction when
     // rendered.
     virtual void setFlipped(bool) = 0;
 
     // Sets the rect in UV space of the texture that is mapped to the layer
     // bounds.
     virtual void setUVRect(const WebFloatRect&) = 0;
 
     // Sets whether every pixel in this layer is opaque. Defaults to false.
     virtual void setOpaque(bool) = 0;
 
     // Sets whether this layer's texture has premultiplied alpha or not. Defaults to true.
     virtual void setPremultipliedAlpha(bool) = 0;
 
     // Indicates that the most recently provided texture ID is about to be modified externally.
     virtual void willModifyTexture() = 0;
 
     // Sets whether this context should be rate limited by the compositor. Rate limiting works by blocking
     // invalidate() and invalidateRect() calls if the compositor is too many frames behind.
     virtual void setRateLimitContext(bool) = 0;
 };
 
 } // namespace WebKit
 
 #endif // WebExternalTextureLayer_h