IWYU in ash::UserWallpaperDelegate

BUG=82098

Review URL: https://codereview.chromium.org/191993002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256367 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256367
[Mac] Add a custom avatar button style for themed windows.

BUG=348915
TEST=With the --new-profile-management flag enabled, switch to a profile that is using a theme. You should see a slightly-differently-styled avatar button, with a more opaque background than the native/guest profile windows has.

Review URL: https://codereview.chromium.org/187633005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256368 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256368