Automatically add extra CQ trybots for predetermined paths

Automatically add extra CQ trybots for predetermined paths

If the CL does not contain a "CQ_EXTRA_TRYBOTS=" section then it constructs one from the paths modified in your CL.

If you already have an existing "CQ_EXTRA_TRYBOTS=" section in your CL then it parses it, preserves your options, and only adds the builders and masters that were missing.

Also ensures no trybots are repeated (i.e. each master trybot combination only shows up once).

And I killed the hashtags feature in this CL, nobody was using it.


BUG=skia:4364
Committed: https://skia.googlesource.com/skia/+/5827653e4271e6f33d2dbd6ac088a6de80fbcea7

[rmistry, 2015-10-01 14:53:17]

rmistry@google.com changed reviewers:
+ mtklein@google.com

[mtklein, 2015-10-01 15:09:44]

lgtm

[rmistry, 2015-10-01 15:17:25]

The CQ bit was checked by rmistry@google.com

[rmistry, 2015-10-01 15:17:25]

The patchset sent to the CQ was uploaded after l-g-t-m from mtklein@google.com
Link to the patchset: https://codereview.chromium.org/1383743002/#ps60001
(title: "Rebase")

[commit-bot: I haz the power, 2015-10-01 15:17:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1383743002/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1383743002/60001

[commit-bot: I haz the power, 2015-10-01 15:24:09]

Committed patchset #4 (id:60001) as
https://skia.googlesource.com/skia/+/5827653e4271e6f33d2dbd6ac088a6de80fbcea7