Revert 234367 "Base: Make RegistryOverrideManager support sharde..."

> Base: Make RegistryOverrideManager support sharded/parallel tests.
> 
> BUG=314800
> TBR=ajwong@chromium.org
> 
> Review URL: https://codereview.chromium.org/57423008

TBR=tommycli@chromium.org

Review URL: https://codereview.chromium.org/69793004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234627 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234627