Refactor WebRTC master configs.

Refactor WebRTC master configs.

This change the WebRTC builder configurations to be more like the
other waterfalls. The Subversion URL, branch and custom deps variables
were used in the past for configuring builders for different branches
and other customizations.

TEST=presubmit
BUG=none

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=208455

[kjellander_chromium, 2013-06-19 09:52:48]

Some cleanup to improve readability.

https://codereview.chromium.org/16959006/diff/1/masters/master.client.webrtc/...
File masters/master.client.webrtc/master_linux_cfg.py (right):

https://codereview.chromium.org/16959006/diff/1/masters/master.client.webrtc/...
masters/master.client.webrtc/master_linux_cfg.py:102: # Android.
Not sure why the diff looks odd here, nothing has changed except the indent.

https://codereview.chromium.org/16959006/diff/1/masters/master.client.webrtc/...
File masters/master.client.webrtc/master_win_cfg.py (right):

https://codereview.chromium.org/16959006/diff/1/masters/master.client.webrtc/...
masters/master.client.webrtc/master_win_cfg.py:11: def win():
It's just indent changes below (except the 'trunk' branch for the Scheduler).

[Mike Stip (use stip instead), 2013-06-21 19:50:03]

lgtm

[commit-bot: I haz the power, 2013-06-25 08:49:18]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/kjellander@chromium.org/16959006/2001

[commit-bot: I haz the power, 2013-06-25 08:50:05]

Change committed as 208455