Thread priority sticked to REALTIME_AUDIO on Linux

Thread priority sticked to REALTIME_AUDIO on Linux

After changing the thread priority to REALTIME_AUDIO, the priority could
not be changed any more because the scheduling policy was changed to
SCHED_RR by pthreads. SCHED_OTHER is UNIX nice based scheduling policy
and it should be set to make setpriority() for other priorities just work.

BUG=468793
Committed: https://crrev.com/e95fe12752e1b0920e60add6722caacdf980b3ae
Cr-Commit-Position: refs/heads/master@{#336085}

[Takashi Toyoshima, 2015-06-24 03:22:45]

toyoshim@chromium.org changed reviewers:
+ gab@chromium.org, thestig@chromium.org

[Takashi Toyoshima, 2015-06-24 03:24:36]

split from https://codereview.chromium.org/1193303002/
There is no real use case in chromium code base as far as I understand, but just
in case.
PTAL.

[Lei Zhang, 2015-06-25 01:57:47]

lgtm

[Takashi Toyoshima, 2015-06-25 02:29:10]

The CQ bit was checked by toyoshim@chromium.org

[commit-bot: I haz the power, 2015-06-25 02:29:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1205703005/1

[commit-bot: I haz the power, 2015-06-25 03:17:30]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-25 03:18:23]

Patchset 1 (id:??) landed as
https://crrev.com/e95fe12752e1b0920e60add6722caacdf980b3ae
Cr-Commit-Position: refs/heads/master@{#336085}