deps2git: Improve support for WebRTC and its deps.

* Remove old unused WebRTC URLs (stable branch was removed
  about a year ago).
* Make the WebRTC matching more generic, so it can match both
  trunk and deps. This will add support for:
  - deps/third_party/junit 
  - deps/third_party/openmax  
  - deps/third_party/winsdk_samples_v71
  and thus the special case for openmax can be removed.

BUG=419516
TESTED=Passing build with:
scripts/tools/run_recipe.py webrtc/standalone buildername="Linux64 Debug" mastername=client.webrtc slavename=x revision='"7414"' use_mirror=True
when combined with https://codereview.chromium.org/472963003/

Review URL: https://codereview.chromium.org/627493002

git-svn-id: http://src.chromium.org/svn/trunk/tools/deps2git@292399 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
2 files changed