Fix non-working battery status manager on Linux.

Fix non-working battery status manager on Linux.

The change in https://crrev.com/2438a3e2acb1318a4e59c78764b532bac3649161
removed the call to start the notification thread and instead always returned
"false".

This CL fixes this by starting the thread (and thus actually getting status
changes).

BUG=420623
R=timvolodine@chromium.org

Committed: https://crrev.com/6571bc9c6dbc7486326f26292a5e351b938d18a7
Cr-Commit-Position: refs/heads/master@{#342343}

[joachim, 2015-08-04 12:34:43]

ptal

[timvolodine, 2015-08-07 12:55:45]

On 2015/08/04 12:34:43, joachim wrote:
> ptal

thanks joachim, good catch! must have been a typo in the mentioned CL.
lgtm

[joachim, 2015-08-07 12:59:14]

The CQ bit was checked by jbauch@webrtc.org

[commit-bot: I haz the power, 2015-08-07 12:59:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1263353004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1263353004/1

[commit-bot: I haz the power, 2015-08-07 13:39:30]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-07 13:40:09]

Patchset 1 (id:??) landed as
https://crrev.com/6571bc9c6dbc7486326f26292a5e351b938d18a7
Cr-Commit-Position: refs/heads/master@{#342343}