Optimize png files in chrome/app/theme

Processed 38 files (out of 53 files) in 00:06:48s
Result : 22812 => 13756 bytes (9056 bytes : 39 %)

BUG=297044
TBR=sky@chromium.org

Review URL: https://codereview.chromium.org/24335007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224751 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224751