Battery Status API: add UMA logging for Windows.

Battery Status API: add UMA logging for Windows.

Adds UMA logging to track if any batteries were present
at the start of Battery Status API.

BUG=

Committed: https://crrev.com/cbeee75bd0fcae4c97e2ad2629053a53da14e940
Cr-Commit-Position: refs/heads/master@{#296278}

[timvolodine, 2014-09-12 15:17:01]

timvolodine@chromium.org changed reviewers:
+ isherman@chromium.org, mvanouwerkerk@chromium.org

[timvolodine, 2014-09-12 15:17:01]

one more platform..

[Ilya Sherman, 2014-09-12 19:32:58]

Histograms LGTM % a suggestion:

https://codereview.chromium.org/556873004/diff/1/tools/metrics/histograms/his...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/556873004/diff/1/tools/metrics/histograms/his...
tools/metrics/histograms/histograms.xml:38097: +  <int value="2"
label="Unknown"/>
nit: It's often best to put the "Unknown" bucket first, in case you're able to
improve your code to distinguish between more battery quantities in the future.

[Michael van Ouwerkerk, 2014-09-15 12:17:58]

lgtm

[timvolodine, 2014-09-23 19:04:39]

https://codereview.chromium.org/556873004/diff/1/tools/metrics/histograms/his...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/556873004/diff/1/tools/metrics/histograms/his...
tools/metrics/histograms/histograms.xml:38097: +  <int value="2"
label="Unknown"/>
On 2014/09/12 19:32:58, Ilya Sherman wrote:
> nit: It's often best to put the "Unknown" bucket first, in case you're able to
> improve your code to distinguish between more battery quantities in the
future.

Done.

[timvolodine, 2014-09-23 21:55:58]

The CQ bit was checked by timvolodine@chromium.org

[commit-bot: I haz the power, 2014-09-23 21:59:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/556873004/40001

[commit-bot: I haz the power, 2014-09-23 22:07:12]

Committed patchset #3 (id:40001) as 3e1354763012982654f991434433e637a5acd1f2

[commit-bot: I haz the power, 2014-09-23 22:07:49]

Patchset 3 (id:??) landed as
https://crrev.com/cbeee75bd0fcae4c97e2ad2629053a53da14e940
Cr-Commit-Position: refs/heads/master@{#296278}