Revert of Re-land: cc: Use worker context for one-copy tile initialization.

Revert of Re-land: cc: Use worker context for one-copy tile initialization. (patchset #29 id:560001 of https://codereview.chromium.org/1230203007/ )

Reason for revert:
Sorry Dave. I'm reverting as this broke mandoline. To see the breakage build mandoline:all, and run with:
mandoline --oopif-always-create-new-frame-tree http://phuang.github.io/iframe.html .

We do have mandoline tests that run, but they run with the code path  gfx::GLSurfaceTestSupport::InitializeOneOff(), which is why they likely still pass. I'll see about making the tests not run with that config.

Original issue's description:
> Re-land: cc: Use worker context for one-copy tile initialization.
>
> This moves management of staging resources to
> OneCopyTileTaskWorkerPool class. This makes it possible
> to use a worker context to issue and detect when copy
> operations complete.
>
> BUG=490295
> TBR=jamesr@chromium.org, sky@chromium.org
> CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
>
> Committed: https://crrev.com/af0ab609b53c64ce43172be42e20e7ca8beab497
> Cr-Commit-Position: refs/heads/master@{#343947}

TBR=jamesr@chromium.org,kbr@chromium.org,piman@chromium.org,primiano@chromium.org,vmiura@chromium.org,vmpstr@chromium.org,reveman@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=490295
Committed: https://crrev.com/c4967eface72bc99452d8a83800c7cdd19a872ee
Cr-Commit-Position: refs/heads/master@{#344042}

[sky, 2015-08-18 21:44:39]

Created Revert of Re-land: cc: Use worker context for one-copy tile
initialization.

[commit-bot: I haz the power, 2015-08-18 21:44:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1298143003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1298143003/1

[commit-bot: I haz the power, 2015-08-18 21:46:10]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-18 21:46:56]

Patchset 1 (id:??) landed as
https://crrev.com/c4967eface72bc99452d8a83800c7cdd19a872ee
Cr-Commit-Position: refs/heads/master@{#344042}