[chromium] Move paintRenderedResultsToCanvas code into DrawingBuffer

[chromium] Move paintRenderedResultsToCanvas code into DrawingBuffer
https://bugs.webkit.org/show_bug.cgi?id=84066

Patch by James Robinson <jamesr@chromium.org> on 2012-04-16
Reviewed by Adrienne Walker.

WebGLLayerChromium used to be responsible for the readback path for software painting WebGL canvases (for
printing, etc), but this path no longer has any compositor interaction. This moves the code into
DrawingBufferChromium which is responsible for managing the front / back buffers for WebGL.

* platform/graphics/chromium/DrawingBufferChromium.cpp:
(WebCore::DrawingBuffer::paintCompositedResultsToCanvas):
* platform/graphics/chromium/WebGLLayerChromium.cpp:
* platform/graphics/chromium/WebGLLayerChromium.h:
(WebGLLayerChromium):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@114344 268f45cc-cd09-0410-ab3c-d52691b4dbfc