Revert of Fix assorted issues with remote CoreAnimation (patchset #2 of https://codereview.chromium.org/516643002/)

Reason for revert:
Speculatively reverting to see if this helps the mac perf bots:
https://code.google.com/p/chromium/issues/detail?id=408673

Original issue's description:
> Fix assorted issues with remote CoreAnimation
>
> These issues came up while running for a few days with the
> flag --enable-remote-core-animation.
>
> Fix flashes of old frames by hooking up the DiscardBackbuffer (which
> happens when being made non-visible) to re-set the CAContext and
> CALayer (so the browser gets a new one with new content for the next
> frame).
>
> Add support for disabling vsync by using setNeedsDisplay to draw.
>
> Change the backpressure mechanism to rely on the browser to apply
> backpressure in its compositor via the cc:: output surface.
>
> Add a ScopedSetGLToRealGLApi structure to ensure that we are talking
> to the real GL API while in the CoreAnimation callback.
>
> BUG=312462
>
> Committed: https://chromium.googlesource.com/chromium/src/+/3b6aee8ed0393d852ed21fae78f539ffffe3e8f8

TBR=piman@chromium.org,ccameron@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=312462

Review URL: https://codereview.chromium.org/517733002

Cr-Commit-Position: refs/heads/master@{#292438}
11 files changed