[tracing] Fix HostDiscardable dump provider to register on the right thread

[tracing] Fix HostDiscardable dump provider to register on the right thread

The HostDiscardableSharedMemoryManager is destroyed when shutting down
and the dump provider is unregistered. But, the dump provider is
registered with no task runner which causes races in memory dumps. This
CL fixes it to register on right thread.

BUG=643438
Committed: https://crrev.com/74dde3a9ea3fef4b5e302040b7eebea2fd7b9422
Cr-Commit-Position: refs/heads/master@{#418592}

[ssid, 2016-09-13 21:47:19]

ssid@chromium.org changed reviewers:
+ primiano@chromium.org

[ssid, 2016-09-13 21:47:19]

Hi, looks like this could cause crashes on slow reports which show up in the
crash reports.
I think we thought the HostDiscardableSharedMemoryManager was a Leaky instance,
but it actually gets deleted.

[Primiano Tucci (use gerrit), 2016-09-14 10:48:29]

primiano@chromium.org changed reviewers:
+ reveman@chromium.org

[Primiano Tucci (use gerrit), 2016-09-14 10:48:30]

don't know too much about lifeftime of discardable manager.
+reveman

RS-LGTM from my viewpoint

[reveman, 2016-09-14 12:27:36]

lgtm

[Primiano Tucci (use gerrit), 2016-09-14 12:28:01]

The CQ bit was checked by primiano@chromium.org

[commit-bot: I haz the power, 2016-09-14 12:28:16]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-14 12:35:38]

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

[commit-bot: I haz the power, 2016-09-14 12:35:39]

Try jobs failed on following builders:
  mac_chromium_compile_dbg_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)

[ssid, 2016-09-14 15:59:23]

ssid@chromium.org changed reviewers:
+ avi@chromium.org

[ssid, 2016-09-14 15:59:24]

+avi ptal, thanks.

[ssid, 2016-09-14 15:59:38]

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

[commit-bot: I haz the power, 2016-09-14 16:00:09]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Avi (use Gerrit), 2016-09-14 16:05:46]

lgtm

stamp

[commit-bot: I haz the power, 2016-09-14 16:49:14]

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

[commit-bot: I haz the power, 2016-09-14 16:49:15]

Dry run: This issue passed the CQ dry run.

[ssid, 2016-09-14 16:51:49]

The CQ bit was checked by ssid@chromium.org

[ssid, 2016-09-14 16:51:50]

The patchset sent to the CQ was uploaded after l-g-t-m from
primiano@chromium.org, reveman@chromium.org
Link to the patchset: https://codereview.chromium.org/2334343002/#ps20001
(title: "use Get.")

[commit-bot: I haz the power, 2016-09-14 16:52:08]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-14 16:56:42]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-09-14 16:58:41]

Description was changed from

==========
[tracing] Fix HostDiscardable dump provider to register on the right thread

The HostDiscardableSharedMemoryManager is destroyed when shutting down
and the dump provider is unregistered. But, the dump provider is
registered with no task runner which causes races in memory dumps. This
CL fixes it to register on right thread.

BUG=643438
==========

to

==========
[tracing] Fix HostDiscardable dump provider to register on the right thread

The HostDiscardableSharedMemoryManager is destroyed when shutting down
and the dump provider is unregistered. But, the dump provider is
registered with no task runner which causes races in memory dumps. This
CL fixes it to register on right thread.

BUG=643438

Committed: https://crrev.com/74dde3a9ea3fef4b5e302040b7eebea2fd7b9422
Cr-Commit-Position: refs/heads/master@{#418592}
==========

[commit-bot: I haz the power, 2016-09-14 16:58:42]

Patchset 2 (id:??) landed as
https://crrev.com/74dde3a9ea3fef4b5e302040b7eebea2fd7b9422
Cr-Commit-Position: refs/heads/master@{#418592}