Requesting background permission only when user is opted in to GN.

BUG=164227
TEST=Opt the user out and in, and check that next poll sets/unsets background permission correspondingly.

Review URL: https://codereview.chromium.org/55123002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232464 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed