'Add a description' is not enough to know what the test is about. Added
some more info.

BUG=

Review URL: https://codereview.chromium.org/313523002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@274393 0039d316-1c4b-4281-b951-d872f2087c98