[Mac] Resources for the new avatar button to be used in themed windows.

BUG=348915
R=oshima@chromium.org

Review URL: https://codereview.chromium.org/191073002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255946 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255946