Don't compile assert when signing-in from the avatar bubble.

BUG=348999

Review URL: https://codereview.chromium.org/180583003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255038 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255038