Use base/threading interface instead of calling Win32 API directly

Use base/threading interface instead of calling Win32 API directly

VideoRendererImpl calls Win32 API to change a thread priority, but it
should be changed via base/threading interface to make code portable.

BUG=468793
Committed: https://crrev.com/4f7e20480c87ce02fc8ac93f9af5fc1ea1f7c24e
Cr-Commit-Position: refs/heads/master@{#336735}

[Takashi Toyoshima, 2015-06-30 03:48:49]

toyoshim@chromium.org changed reviewers:
+ scherkus@chromium.org

[Takashi Toyoshima, 2015-06-30 03:50:51]

Hi scherkus, I find this in the midst of removing id() and platform_handle()
interfaces from PlatformThread in https://codereview.chromium.org/1207823004/.
Can you review this?

[Takashi Toyoshima, 2015-06-30 03:51:34]

oops, status shows "not reviewing"
I'll find another reviewer.

[Takashi Toyoshima, 2015-06-30 03:52:05]

toyoshim@chromium.org changed reviewers:
+ dalecurtis@chromium.org
- scherkus@chromium.org

[Takashi Toyoshima, 2015-06-30 03:52:27]

DaleCurtis, can you take a look?

[DaleCurtis, 2015-06-30 05:39:36]

lgtm

[Takashi Toyoshima, 2015-06-30 05:51:14]

The CQ bit was checked by toyoshim@chromium.org

[commit-bot: I haz the power, 2015-06-30 05:51:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1217943003/1

[commit-bot: I haz the power, 2015-06-30 07:08:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-30 07:09:01]

Patchset 1 (id:??) landed as
https://crrev.com/4f7e20480c87ce02fc8ac93f9af5fc1ea1f7c24e
Cr-Commit-Position: refs/heads/master@{#336735}