scheduler: Encapsulate TaskQueueManager inside SchedulerHelper

scheduler: Encapsulate TaskQueueManager inside SchedulerHelper

Isolate TaskQueueManager inside SchedulerHelper so that classes that
embed SchedulerHelper don't end up adding dependencies to
TaskQueueManager in a uncontrolled way.

No functional changes.

Committed: https://crrev.com/f08a17169d8e41d862b5510cf159a513df885730
Cr-Commit-Position: refs/heads/master@{#325235}

[Sami, 2015-04-13 12:37:14]

skyostil@chromium.org changed reviewers:
+ alexclarke@chromium.org, rmcilroy@chromium.org

[rmcilroy, 2015-04-13 14:42:55]

lgtm, thanks!

[alex clarke (OOO till 29th), 2015-04-13 14:44:33]

I think you'll need to rebase, but it looks good otherwise.

[Sami, 2015-04-15 11:08:43]

The CQ bit was checked by skyostil@chromium.org

[Sami, 2015-04-15 11:08:44]

The patchset sent to the CQ was uploaded after l-g-t-m from
rmcilroy@chromium.org
Link to the patchset: https://codereview.chromium.org/1059323003/#ps40001
(title: "Rebased.")

[commit-bot: I haz the power, 2015-04-15 11:08:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1059323003/40001

[commit-bot: I haz the power, 2015-04-15 12:09:38]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-15 12:09:39]

Try jobs failed on following builders:
  linux_android_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_android_r...)

[Sami, 2015-04-15 12:23:41]

The CQ bit was checked by skyostil@chromium.org

[Sami, 2015-04-15 12:23:42]

The patchset sent to the CQ was uploaded after l-g-t-m from
rmcilroy@chromium.org
Link to the patchset: https://codereview.chromium.org/1059323003/#ps60001
(title: "GCC build fix.")

[commit-bot: I haz the power, 2015-04-15 12:24:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1059323003/60001

[commit-bot: I haz the power, 2015-04-15 13:28:30]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-04-15 13:29:23]

Patchset 4 (id:??) landed as
https://crrev.com/f08a17169d8e41d862b5510cf159a513df885730
Cr-Commit-Position: refs/heads/master@{#325235}