add _thumb variants for arm devices

BUG=
R=djsollen@google.com

Author: mtklein@google.com

Review URL: https://chromiumcodereview.appspot.com/19024002

git-svn-id: http://skia.googlecode.com/svn/trunk@10001 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed