bin/try: Add support for select Chromium trybots

These are hard-coded in update_meta_config.py, which is used to set the
list of trybots in Gerrit.

Bug: skia:
Change-Id: I6e512e4cb59974e27e8954cf5134c70068e716f3
Reviewed-on: https://skia-review.googlesource.com/60521
Reviewed-by: Ravi Mistry <rmistry@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
2 files changed