[scheduler]: Fix tracing issues with nested IdlePeriod trace events.

[scheduler]: Fix tracing issues with nested IdlePeriod trace events.

Avoids using nested async trace events and moves back to async step-into
because otherwise tracing seems to get messed up under certain circumstances.

Also removes a DCHECK which could fire when in a nested message loop.

BUG=522843, 504656
Committed: https://crrev.com/40acc969c52775e2421f3731caf5f7f810beedcd
Cr-Commit-Position: refs/heads/master@{#344750}

[rmcilroy, 2015-08-20 18:41:53]

rmcilroy@chromium.org changed reviewers:
+ skyostil@google.com

[rmcilroy, 2015-08-20 18:41:54]

Sami, PTAL, thanks.

[rmcilroy, 2015-08-20 19:06:47]

Patchset #1 (id:1) has been deleted

[rmcilroy, 2015-08-20 19:06:58]

The CQ bit was checked by rmcilroy@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-20 19:08:00]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1292983005/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1292983005/20001

[commit-bot: I haz the power, 2015-08-20 20:42:52]

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

[commit-bot: I haz the power, 2015-08-20 20:42:52]

Dry run: Try jobs failed on following builders:
  linux_chromium_asan_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[Sami, 2015-08-21 10:46:58]

skyostil@chromium.org changed reviewers:
+ skyostil@chromium.org

[Sami, 2015-08-21 10:46:58]

Thanks, lgtm.

https://codereview.chromium.org/1292983005/diff/20001/components/scheduler/ch...
File components/scheduler/child/idle_helper.cc (left):

https://codereview.chromium.org/1292983005/diff/20001/components/scheduler/ch...
components/scheduler/child/idle_helper.cc:282:
DCHECK(IsInIdlePeriod(state_.idle_period_state()));
Would you also mind adding a TODO about not forgetting which task queue the task
is associated in TQM where we deal with posting non-nestable tasks?

[rmcilroy, 2015-08-21 10:57:47]

https://codereview.chromium.org/1292983005/diff/20001/components/scheduler/ch...
File components/scheduler/child/idle_helper.cc (left):

https://codereview.chromium.org/1292983005/diff/20001/components/scheduler/ch...
components/scheduler/child/idle_helper.cc:282:
DCHECK(IsInIdlePeriod(state_.idle_period_state()));
On 2015/08/21 10:46:58, Sami wrote:
> Would you also mind adding a TODO about not forgetting which task queue the
task
> is associated in TQM where we deal with posting non-nestable tasks?

Added (as TODO(skyostil) ;)).

[rmcilroy, 2015-08-21 10:57:50]

The CQ bit was checked by rmcilroy@chromium.org

[rmcilroy, 2015-08-21 10:57:50]

The patchset sent to the CQ was uploaded after l-g-t-m from
skyostil@chromium.org
Link to the patchset: https://codereview.chromium.org/1292983005/#ps40001
(title: "Add todo")

[commit-bot: I haz the power, 2015-08-21 10:58:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1292983005/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1292983005/40001

[commit-bot: I haz the power, 2015-08-21 13:24:38]

Committed patchset #2 (id:40001)

[commit-bot: I haz the power, 2015-08-21 13:25:12]

Patchset 2 (id:??) landed as
https://crrev.com/40acc969c52775e2421f3731caf5f7f810beedcd
Cr-Commit-Position: refs/heads/master@{#344750}