Notify the new avatar button when the active profile name has changed.

BUG=305041
TEST=With the --new-profile-management flag enabled, edit the name of
the active profile in chrome://settings. The text displayed by the
new avatar button should update immediately.

Review URL: https://codereview.chromium.org/31993004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229958 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229958