metrics: add metrics for wake on WiFi throttling

metrics: add metrics for wake on WiFi throttling

Add metric to log whether or not wake on WiFi is disabled
in the duration of a single suspend because of excessive
dark resume wakes.

BUG=chrome-os-partner:35518
TEST=None.

Committed: https://crrev.com/36f5b4ab7fb8330bc3267f30c88a2026d09b40d5
Cr-Commit-Position: refs/heads/master@{#313453}

[samueltan1, 2015-01-27 17:47:49]

samueltan@google.com changed reviewers:
+ asvitkine@chromium.org, samueltan@google.com

[samueltan1, 2015-01-27 17:47:49]

PTL, thanks.

[Alexei Svitkine (slow), 2015-01-27 17:50:01]

lgtm

[samueltan1, 2015-01-27 17:50:30]

The CQ bit was checked by samueltan@google.com

[commit-bot: I haz the power, 2015-01-27 17:51:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/876373002/1

[commit-bot: I haz the power, 2015-01-27 17:58:28]

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

[commit-bot: I haz the power, 2015-01-27 17:58:29]

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

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

[samueltan1, 2015-01-28 05:17:21]

Rebased with ToT. Inheriting LGTM.

[samueltan1, 2015-01-28 05:17:44]

The CQ bit was checked by samueltan@google.com

[commit-bot: I haz the power, 2015-01-28 05:18:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/876373002/20001

[commit-bot: I haz the power, 2015-01-28 06:31:04]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-01-28 06:33:40]

Patchset 2 (id:??) landed as
https://crrev.com/36f5b4ab7fb8330bc3267f30c88a2026d09b40d5
Cr-Commit-Position: refs/heads/master@{#313453}