WebRTC recipes: Switch tryserver.webrtc to recipes (take 2)
WebRTC recipes: Switch tryserver.webrtc to recipes (take 2)

Second attempt of switching the tryserver.webrtc master
to recipes. Previous attempt in
https://codereview.chromium.org/306473002/
was reverted since the apply patch step failed, which
has been fixed in https://codereview.chromium.org/302003010/

The lack of test filter support is a known issue being
discussed briefly in https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/0Q-hzq5YE2Q/discussion

We might just have to add compile-only trybots for the most
common test case (that is to just compile).

BUG=346198
TEST=Tried submitting local patches to locally running master+slave on Linux and Windows.

Review URL: https://codereview.chromium.org/306013006

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@274228 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build