GitLab

- os.path is provided by input_api, and it's preferred to use it
- time does not seem to be used any more
- input_api.change.AffectedFiles() with a "starts with my dir" filter
  is equivalent to input_api.AffectedFiles(); also, harness file_filter=
- os.path.split()[1] is equivalent to os.path.basename(), which is more
  readable, IMO

R=calamity@chromium.org
BUG=none
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2599593003
Cr-Commit-Position: refs/heads/master@{#440937}