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

Source/Platform/chromium/public/WebExternalTextureLayer.h

Index: Source/Platform/chromium/public/WebExternalTextureLayer.h
diff --git a/Source/Platform/chromium/public/WebExternalTextureLayer.h b/Source/Platform/chromium/public/WebExternalTextureLayer.h
index 568dd31730914d657291b6c6465ccaa7f0189228..b25dd815b639a66b1feb6e27259df84c9da9d227 100644
--- a/Source/Platform/chromium/public/WebExternalTextureLayer.h
+++ b/Source/Platform/chromium/public/WebExternalTextureLayer.h
@@ -46,6 +46,9 @@ public:
 
     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;