[telemetry] Use SetEvent signals instead of web server for IPPET power monitor.

[telemetry] Use SetEvent signals instead of web server for IPPET power monitor.

Hopefully this will reduce flake and overhead from running the web server.


BUG=336558
TEST=Enable IppetPowerMonitor.CanMonitorPower(), then tools/telemetry/run_tests ippet on Windows.

Committed: https://crrev.com/cb25fdedc138dcfd72f2293553a7d9616ff6396f
Cr-Commit-Position: refs/heads/master@{#292093}

[dtu, 2014-08-27 00:56:28]

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

[tonyg, 2014-08-27 01:00:09]

lgtm

woot :)

Any idea what the cycle time is like w/ this patch?

[dtu, 2014-08-27 01:02:21]

On 2014/08/27 01:00:09, tonyg wrote:
> lgtm
> 
> woot :)
> 
> Any idea what the cycle time is like w/ this patch?

Unfortunately, I didn't see any difference in the unit test cycle time with this
patch :( It was 2.6s either way.
Although the first run after making changes is always noticeably longer, 4.4s. I
guess it's Python compile time!?

[dtu, 2014-08-27 01:14:06]

The CQ bit was checked by dtu@chromium.org

[commit-bot: I haz the power, 2014-08-27 01:15:25]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dtu@chromium.org/504333003/1

[commit-bot: I haz the power, 2014-08-27 03:13:07]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  mac_gpu_retina_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu_retina_tr...)
  linux_chromium_chromeos_rel_swarming on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[commit-bot: I haz the power, 2014-08-27 03:55:26]

Committed patchset #1 (1) as ad9843c5ebf548e649dc635099145744a1137dfa

[commit-bot: I haz the power, 2014-09-10 02:49:36]

Patchset 1 (id:??) landed as
https://crrev.com/cb25fdedc138dcfd72f2293553a7d9616ff6396f
Cr-Commit-Position: refs/heads/master@{#292093}