Enable declarativeContent on the dev channel.

See https://groups.google.com/a/chromium.org/d/topic/apps-dev/Y4DWHi6r7Zk/discussion for the API review.

BUG=172011

Review URL: https://codereview.chromium.org/54273010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234442 0039d316-1c4b-4281-b951-d872f2087c98
Invalidate auth token during logoutUserForReauthentication().

BUG=307642

Review URL: https://codereview.chromium.org/68403002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234443 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234443