Enable GPU Control lists on Linux.

This is the Linux follow-up to http://crrev.com/228530.

TBR=zmo, vangelis, jcivelli
BUG=295799

Review URL: https://codereview.chromium.org/27334002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229209 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229209