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

Revert of Re-land: cc: Use worker context for one-copy tile initialization. (patchset #22 id:420001 of https://codereview.chromium.org/1230203007/ )

Reason for revert:
I'm sorry, but this patch definitely causes failures of one of the context_lost tests on Windows on multiple bots as described in https://code.google.com/p/chromium/issues/detail?id=490295#c15 . I'm sorry the CQ isn't catching these, and I'm not sure why it isn't -- but it's important to fix these failures rather than leaving them on the tree.

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
> CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
>
> Committed: https://crrev.com/a6b998600660f34bcce9fbc2c75bbc0a3f7f03cc
> Cr-Commit-Position: refs/heads/master@{#342567}

TBR=piman@chromium.org,primiano@chromium.org,vmiura@chromium.org,vmpstr@chromium.org,reveman@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=490295

Review URL: https://codereview.chromium.org/1282183002

Cr-Commit-Position: refs/heads/master@{#342568}