Revert of aura: Remove old GL paths from RenderWidgetHostViewAura.

Revert of aura: Remove old GL paths from RenderWidgetHostViewAura. (https://codereview.chromium.org/131443007/)

Reason for revert:
This is causing many virtual/threaded/transitions and virtual/threaded/animations tests to time out.
Some of them are timing out flakily, some are consistent.

Here is what I’ve seen so far:

virtual/threaded/transitions/move-after-transition.html - consistent time outs.

virtual/threaded/transitions/cubic-bezier-overflow-svg-length.html - flaky time outs
virtual/threaded/transitions/change-duration-during-transition.html - flaky time outs
virtual/threaded/animations/cross-fade-background-image.html - flaky ImageOnlyFailure, looks like it is related.

Original issue's description:
> aura: Remove old GL paths from RenderWidgetHostViewAura.
> 
> Frames from the renderer are either legacy software,
> software compositing, or ubercomp. Remove the old GL composited
> paths that are no longer in use.
> 
> For layout tests, put them into composited mailbox mode, and
> instead of sending the frame to the browser at all, just put the
> frame in a post task to ack back directly to the renderer.
> 
> R=piman
> BUG=332998
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=249226
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=258742

TBR=piman@chromium.org,fsamuel@chromium.org,phajdan.jr@chromium.org,jamesr@chromium.org,danakj@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=332998
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=258891

[vsevik, 2014-03-24 08:42:00]

Created Revert of aura: Remove old GL paths from RenderWidgetHostViewAura.

[commit-bot: I haz the power, 2014-03-24 08:42:01]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/vsevik@chromium.org/209903002/1

[commit-bot: I haz the power, 2014-03-24 08:42:52]

Change committed as 258891