Enables only building targets effected by changed on a couple of bots

BUG=109173
TEST=none
R=jam@chromium.org
TBR=jam@chromium.org

Review URL: https://codereview.chromium.org/492293002

git-svn-id: http://src.chromium.org/chrome/trunk/src/testing@291103 4ff67af0-8c30-449e-8e8b-ad334ec8d88c