Add omnibox popup images with combined border/shadow.

Add additional transparent images for omniboxes in popup
windows. This should've been part of r242536.

BUG=233364
TBR=pkasting@chromium.org,oshima@chromium.org

Review URL: https://codereview.chromium.org/119153003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242542 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242542