aura: Change shared context to be offscreen for arm

aura: Change shared context to be offscreen for arm

ARM drivers don't like to have 2 EGLSurface on the same Window. So we need to
make the UI shared context offscren.
This also requires the image transport surface to be an "offscreen" GLSurface (a
pbuffer), however the GLES2Decoder needs to be "onscreen" (i.e. it calls
SwapBuffers on the surface instead managing the offscreen buffers itself).
So this decouples the 2 notions of "offscreen".

BUG=chrome-os-partner:8284
TEST=gpu_unittests. Aura chrome --ui-use-gpu-process with poster circle and webgl on tegra, lumpy, desktop GL. Desktop chrome with poster circle and webgl.


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=131177

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=133975

[piman, 2012-04-06 06:22:01]

apatrick: please review
sky: OWNERS in content/browser/renderer_host

[sky, 2012-04-06 15:59:15]

LGTM

[apatrick_chromium, 2012-04-06 17:55:36]

lgtm

[commit-bot: I haz the power, 2012-04-06 18:02:26]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/piman@chromium.org/10007034/1

[commit-bot: I haz the power, 2012-04-06 20:11:46]

Change committed as 131177

[commit-bot: I haz the power, 2012-04-25 16:43:32]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/piman@chromium.org/10007034/1

[commit-bot: I haz the power, 2012-04-25 17:02:27]

Try job failure for 10007034-1 (retry) on win for step "compile" (clobber
build).
It's a second try, previously, step "compile" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win&number...

[commit-bot: I haz the power, 2012-04-25 19:15:19]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/piman@chromium.org/10007034/13004

[commit-bot: I haz the power, 2012-04-25 20:52:25]

Change committed as 133975