Revert 132934 - this change seems to break many webgl related layout tests

Revert 132934 - this change seems to break many webgl related layout tests

Introduction of CHROMIUM_copy_texture extension that respects pixel-store semantics, and allows copying of BGRA textures.

OpenGL ES does not natively allow for copying textures with a BGRA format. The EXT_texture_format_BGRA8888 extension does not specify support for glCopyTexImage calls on these textures.

This extension provides a routine to perform texture copies to/from BGRA-backed textures that also respects the following CHROMIUM pixel storage modifiers:
UNPACK_FLIP_Y_CHROMIUM
UNPACK_PREMULTIPLY_ALPHA_CHROMIUM

This extension will be useful for the following purposes:
- Copying accelerated Canvas2D contents to WebGL textures without a software readback. (And potentially the same for video-webgl texture copies.)
- Copying Canvas2D contents to the compositor backing store.

BUG=101051
TEST=none

Review URL: http://codereview.chromium.org/9968113

TBR=twiz@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=132958