Remove usage of SequencedWorkerPool::GetNamedSequenceToken from content::CreateFileSystemContext.

Remove usage of SequencedWorkerPool::GetNamedSequenceToken from content::CreateFileSystemContext.

SequencedWorkerPool is being deprecated in favor of TaskScheduler.

BUG=667892
Review-Url: https://codereview.chromium.org/2883403002
Cr-Commit-Position: refs/heads/master@{#474638}
Committed: https://chromium.googlesource.com/chromium/src/+/bb731a6137ac921a8aa465613acab752b16f4666

[fdoray, 2017-05-16 19:43:12]

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

[commit-bot: I haz the power, 2017-05-16 19:44:16]

Dry run: 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, 2017-05-16 22:24:50]

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

[commit-bot: I haz the power, 2017-05-16 22:24:50]

Dry run: This issue passed the CQ dry run.

[fdoray, 2017-05-17 14:38:48]

fdoray@chromium.org changed reviewers:
+ tzik@chromium.org

[fdoray, 2017-05-17 14:38:49]

Please take a look.

https://codereview.chromium.org/2883403002/diff/1/content/browser/fileapi/bro...
File content/browser/fileapi/browser_file_system_helper.cc (left):

https://codereview.chromium.org/2883403002/diff/1/content/browser/fileapi/bro...
content/browser/fileapi/browser_file_system_helper.cc:69:
pool->GetNamedSequenceToken("FileAPI"),
Mutual exclusion is guaranteed between tasks posted to SequencedTaskRunners
sharing the same named sequence token. With my CL, no named sequence token is
used, which means that the file SequencedTaskRunners of different
storage::FileSystemContext instances may run their tasks concurrently. Is this
ok?

[fdoray, 2017-05-19 20:07:08]

On 2017/05/17 14:38:49, fdoray wrote:
> Please take a look.
> 
>
https://codereview.chromium.org/2883403002/diff/1/content/browser/fileapi/bro...
> File content/browser/fileapi/browser_file_system_helper.cc (left):
> 
>
https://codereview.chromium.org/2883403002/diff/1/content/browser/fileapi/bro...
> content/browser/fileapi/browser_file_system_helper.cc:69:
> pool->GetNamedSequenceToken("FileAPI"),
> Mutual exclusion is guaranteed between tasks posted to SequencedTaskRunners
> sharing the same named sequence token. With my CL, no named sequence token is
> used, which means that the file SequencedTaskRunners of different
> storage::FileSystemContext instances may run their tasks concurrently. Is this
> ok?

ping

[tzik, 2017-05-25 07:51:51]

lgtm

[fdoray, 2017-05-25 12:11:33]

The CQ bit was checked by fdoray@chromium.org

[commit-bot: I haz the power, 2017-05-25 12:11:42]

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, 2017-05-25 13:44:00]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1495714293767750, "parent_rev":
"bbe9885032f425edbee05e177db0ccc6c52834ad", "commit_rev":
"bb731a6137ac921a8aa465613acab752b16f4666"}

[commit-bot: I haz the power, 2017-05-25 13:44:13]

Description was changed from

==========
Remove usage of SequencedWorkerPool::GetNamedSequenceToken from
content::CreateFileSystemContext.

SequencedWorkerPool is being deprecated in favor of TaskScheduler.

BUG=667892
==========

to

==========
Remove usage of SequencedWorkerPool::GetNamedSequenceToken from
content::CreateFileSystemContext.

SequencedWorkerPool is being deprecated in favor of TaskScheduler.

BUG=667892

Review-Url: https://codereview.chromium.org/2883403002
Cr-Commit-Position: refs/heads/master@{#474638}
Committed:
https://chromium.googlesource.com/chromium/src/+/bb731a6137ac921a8aa465613aca...
==========

[commit-bot: I haz the power, 2017-05-25 13:44:14]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/bb731a6137ac921a8aa465613aca...

[Marijn Kruisselbrink, 2017-07-05 21:11:40]

This CL seems to have introduced data races, as before all FileSystemContexts
shared the same sequence, while now each has their own sequence. It seems
multiple FileSystemContexts might sometimes share a single ObfuscatedFileUtil
instance, which laziliy initializes itself on first use, but can now end up
initializing itself on multiple threads/sequences at the same time... see
https://luci-logdog.appspot.com/v/?s=chromium%2Fbb%2Ftryserver.chromium.linux...
for example (for a test run where the number of threads was increased from 1 to
2 to actually reveal this race).

[Marijn Kruisselbrink, 2017-07-05 21:15:02]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2969293003/ by mek@chromium.org.

The reason for reverting is: Seems to cause data races, since different
FileSystemContexts are no longer sharing the same sequence..