MSan: add test configs for two new browser_tests runners.

Also, add app_shell_browsertests.

BUG=178409
R=glider@chromium.org
TBR=phajdan.jr@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/437813002

git-svn-id: http://src.chromium.org/chrome/trunk/src/testing@286985 4ff67af0-8c30-449e-8e8b-ad334ec8d88c