Remove references to DB thread from unit test.

Remove references to DB thread from unit test.

This removes references to the DB thread from the important sites
usage counter unit test.

BUG=689520

[benwells, 2017-06-27 05:27:19]

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

[commit-bot: I haz the power, 2017-06-27 05:27:35]

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, 2017-06-27 05:55:46]

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

[commit-bot: I haz the power, 2017-06-27 05:55:47]

Dry run: This issue passed the CQ dry run.

[benwells, 2017-06-27 05:59:37]

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

[benwells, 2017-06-27 05:59:37]

am i holding it right?

[fdoray, 2017-06-27 13:28:56]

A better fix would be to remove the |db_thread| argument from the constructor of
QuotaManager and to initialize |db_thread_| with a SequencedTaskRunner returned
by CreateSequencedTaskRunnerWithTraits().

"the component that uses a TaskRunner should be the one that creates it"
https://chromium.googlesource.com/chromium/src/+/47642f05bc6abb99b8df5f3900e5...

Would you feel comfortable doing that change?

https://codereview.chromium.org/2958943002/diff/1/chrome/browser/engagement/i...
File chrome/browser/engagement/important_sites_usage_counter_unittest.cc
(right):

https://codereview.chromium.org/2958943002/diff/1/chrome/browser/engagement/i...
chrome/browser/engagement/important_sites_usage_counter_unittest.cc:85:
content::TestBrowserThreadBundle thread_bundle;
Do not remove the trailing underscore.

[benwells, 2017-07-07 06:22:16]

On 2017/06/27 13:28:56, fdoray (OOO until July 22) wrote:
> A better fix would be to remove the |db_thread| argument from the constructor
of
> QuotaManager and to initialize |db_thread_| with a SequencedTaskRunner
returned
> by CreateSequencedTaskRunnerWithTraits().

That probably should be left to the owners of QuotaManager. I'll assign this one
to whoever is doing storage_partition_impl.cc, which contains a reference to the
DB thread.

> 
> "the component that uses a TaskRunner should be the one that creates it"
>
https://chromium.googlesource.com/chromium/src/+/47642f05bc6abb99b8df5f3900e5...
> 
> Would you feel comfortable doing that change?
> 
>
https://codereview.chromium.org/2958943002/diff/1/chrome/browser/engagement/i...
> File chrome/browser/engagement/important_sites_usage_counter_unittest.cc
> (right):
> 
>
https://codereview.chromium.org/2958943002/diff/1/chrome/browser/engagement/i...
> chrome/browser/engagement/important_sites_usage_counter_unittest.cc:85:
> content::TestBrowserThreadBundle thread_bundle;
> Do not remove the trailing underscore.