Revert 287747 "Make SingleThreadProxy a SchedulerClient"

Revert 287747 "Make SingleThreadProxy a SchedulerClient"
This is a speculative revert to see if issues on Mac bots get resolved.

BrowserTest.WindowOpenClose is e.g. failing on this assert:
ASSERTION FAILED: !active || m_layerTreeView

> Make SingleThreadProxy a SchedulerClient
> 
> This makes ui::Compositor no longer in charge of
> scheduling commits and draws, deferring it to cc::Scheduler.
> 
> Other compositors that use SingleThreadProxy are left calling composite
> synchronously and now pass a flag to indicate that this is their
> intention.  This patch doesn't remove synchronous composite, but now
> makes it mutually exclusive with scheduling.
> 
> BUG=329552, 287250
> 
> Review URL: https://codereview.chromium.org/134623005

TBR=enne@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=287766

[tommi (sloooow) - chröme, 2014-08-06 13:05:27]

Committed patchset #1 manually as r287766 (tree was closed).