Re-land: cc: Cleanup internal::WorkerPoolTaskClient interface.

::CompleteOnOriginThread is now called when RasterWorkerPool has
completed all necessary initialization of resource, including
texture uploads. This improves the WorkerPoolTask/Client interface
significantly and will allow better resource recycling once
::RunReplyOnOriginThread is removed.

BUG=269841

Review URL: https://codereview.chromium.org/170783007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252874 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252874