[Telemetry] Always use ephemeral port chosen by Chrome.

[Telemetry] Always use ephemeral port chosen by Chrome.

This reduces a potential source of flake for desktop Chrome. The
reference builds are now M37 (and I've verified they behave properly)
and stable is now M38.

BUG=379980
Committed: https://crrev.com/f71a95de8adcd6cab36f87d669feda3fb1984896
Cr-Commit-Position: refs/heads/master@{#299621}

[tonyg, 2014-10-13 21:19:54]

tonyg@chromium.org changed reviewers:
+ dtu@chromium.org, kbr@chromium.org

[dtu, 2014-10-14 00:09:41]

lgtm

[Ken Russell (switch to Gerrit), 2014-10-14 05:57:16]

LGTM. Thanks for cleaning this up.

https://codereview.chromium.org/650963003/diff/1/tools/telemetry/telemetry/co...
File tools/telemetry/telemetry/core/browser_options.py (right):

https://codereview.chromium.org/650963003/diff/1/tools/telemetry/telemetry/co...
tools/telemetry/telemetry/core/browser_options.py:248:
group.add_option('--use-devtools-active-port',
We should remove this too after landing this CL and after updating all the
recipes to no longer pass this argument.

[tonyg, 2014-10-15 00:36:45]

The CQ bit was checked by tonyg@chromium.org

[commit-bot: I haz the power, 2014-10-15 00:40:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/650963003/1

[commit-bot: I haz the power, 2014-10-15 01:44:21]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-15 01:46:36]

Patchset 1 (id:??) landed as
https://crrev.com/f71a95de8adcd6cab36f87d669feda3fb1984896
Cr-Commit-Position: refs/heads/master@{#299621}

[tonyg, 2014-10-16 17:26:15]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/659923003/ by tonyg@chromium.org.

The reason for reverting is: Possibly caused flake. Will reland if mistaken.

BUG=424245.