Add chrome/app/theme/mobile[_lit][_1_25x|2x].png files.
I ran PNGCrush and PNGSlim (6,710 bytes -> 814 bytes).

BUG=102709
TEST=none, adding images.

Review URL: https://chromiumcodereview.appspot.com/9651030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@126263 0039d316-1c4b-4281-b951-d872f2087c98