Re-land: Use script in depot_tools to retrieve builders from new cq.cfg

Re-land: Use script in depot_tools to retrieve builders from new cq.cfg

TBR=akuegel@chromium.org, jochen@chromium.org
TEST=ran git-cl-try on this CL on Win, Mac and Linux

Committed: https://crrev.com/2c7fb79b2aad9d924dcbcd663e09f3022884f502
Cr-Commit-Position: refs/heads/master@{#332369}

[Sergiy Byelozyorov, 2015-06-02 09:46:51]

sergiyb@chromium.org changed reviewers:
+ akuegel@chromium.org
- pgervais@chromium.org

[Adrian Kuegel, 2015-06-02 09:50:48]

lgtm

[Sergiy Byelozyorov, 2015-06-02 10:08:41]

The CQ bit was checked by sergiyb@chromium.org

[commit-bot: I haz the power, 2015-06-02 10:09:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1148303006/20001

[commit-bot: I haz the power, 2015-06-02 10:38:48]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-06-02 10:38:50]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[Sergiy Byelozyorov, 2015-06-02 11:14:22]

sergiyb@chromium.org changed reviewers:
+ jochen@chromium.org

[Sergiy Byelozyorov, 2015-06-02 11:14:52]

The CQ bit was checked by sergiyb@chromium.org

[commit-bot: I haz the power, 2015-06-02 11:15:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1148303006/20001

[commit-bot: I haz the power, 2015-06-02 11:36:28]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-06-02 11:37:15]

Patchset 2 (id:??) landed as
https://crrev.com/2c7fb79b2aad9d924dcbcd663e09f3022884f502
Cr-Commit-Position: refs/heads/master@{#332369}

[Peter Beverloo, 2015-06-02 14:36:34]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/1160783004/ by peter@chromium.org.

The reason for reverting is: Breaks the "git cl try" command, see chromium-dev@
and crbug.com/495219.

Traceback (most recent call last):
  File "/b/depot_tools/commit_queue.py", line 28, in <module>
    from cq_client import cq_pb2
  File "/b/depot_tools/third_party/cq_client/cq_pb2.py", line 9, in <module>
    from google.protobuf import symbol_database as _symbol_database
ImportError: cannot import name symbol_database

BUG=495219.