Added command buffer implementation of WebGL which runs in the sandbox.
Added synchronous initialization of the channel to the GPU process, needed
to obey WebGL startup semantics. There are problems with this on the
Windows platform which will be addressed via refactoring in the
GpuProcessHost in a subsequent CL. Implemented offscreen rendering code
path in GGL / GLES2CmdDecoder for Mac OS X.

This new code path is not yet complete for all platforms and is still being
stress tested. The previous in-process WebGL implementation is currently
used when the sandbox is disabled; it will be removed in a subsequent CL.

A one-line code change in WebKit is needed after this CL lands to enable
the new code path.

BUG=29120
TEST=ran WebGL demos on command buffer implementation on Mac

Review URL: http://codereview.chromium.org/1328001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@42879 0039d316-1c4b-4281-b951-d872f2087c98
19 files changed