Have GPUTracer process traces during CommandBuffer Idle time.

Have GPUTracer process traces during CommandBuffer Idle time.

ThreadTaskRunnerHandle is not always available to execute GPUTracer
process commands (IE on android webview), switch to use the command
buffer idle time instead.

R=vmiura@chromium.org
BUG=None
TEST=trybots

Committed: https://crrev.com/ed04ca3ef4560f5d85d4ee788e6716d37c7be644
Cr-Commit-Position: refs/heads/master@{#345672}

[boliu, 2015-08-25 23:35:39]

> ThreadTaskRunnerHandle is not always available to execute GPUTracer process
commands

ie on android webview..

[David Yen, 2015-08-25 23:37:23]

On 2015/08/25 23:35:39, boliu wrote:
> > ThreadTaskRunnerHandle is not always available to execute GPUTracer process
> commands
> 
> ie on android webview..

Modified description to add that.

[David Yen, 2015-08-25 23:38:11]

dyen@chromium.org changed reviewers:
+ zmo@chromium.org

[David Yen, 2015-08-25 23:38:11]

+zmo for review in case vmiura is busy

[vmiura, 2015-08-26 20:54:51]

lgtm

[David Yen, 2015-08-26 20:55:33]

The CQ bit was checked by dyen@chromium.org

[commit-bot: I haz the power, 2015-08-26 20:57:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1314053002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1314053002/1

[commit-bot: I haz the power, 2015-08-26 21:05:09]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-26 21:06:03]

Patchset 1 (id:??) landed as
https://crrev.com/ed04ca3ef4560f5d85d4ee788e6716d37c7be644
Cr-Commit-Position: refs/heads/master@{#345672}