HistoryQuickProviderTest.DeleteMatch thread safety fix.

HistoryQuickProviderTest.DeleteMatch thread safety fix.

history_backend is not supposed to be used except on the history thread.
The existing code manages to run because all of the underlying
sql::Connection statements were generated before test SetUp() completed,
so the previous calls could read statements from the cache without
modifying it.

BUG=537681
Committed: https://crrev.com/f20e6bb6c89853231d3ad519456a1df000eaf3e4
Cr-Commit-Position: refs/heads/master@{#352073}

[Scott Hess - ex-Googler, 2015-09-30 22:34:15]

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

[Scott Hess - ex-Googler, 2015-09-30 22:34:58]

shess@chromium.org changed reviewers:
+ sky@chromium.org

[Scott Hess - ex-Googler, 2015-09-30 22:34:58]

sky@ as OWNER
endegy@ as author of the bits of this test which are problematic (I think).

[commit-bot: I haz the power, 2015-09-30 22:35:57]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1368293012/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1368293012/1

[commit-bot: I haz the power, 2015-09-30 23:50:06]

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

[commit-bot: I haz the power, 2015-09-30 23:50:07]

Dry run: This issue passed the CQ dry run.

[sky, 2015-09-30 23:52:10]

https://chromiumcodereview.appspot.com/1368293012/diff/1/components/history/c...
File components/history/core/browser/history_service.h (right):

https://chromiumcodereview.appspot.com/1368293012/diff/1/components/history/c...
components/history/core/browser/history_service.h:507: bool
PostTaskAndReplyForTest(const base::Closure& task,
THis is effectively duplicating what HistoryDBTask does. Can you use it instead?

[shess1, 2015-10-01 18:07:11]

Convert to HistoryDBTask.

[Scott Hess - ex-Googler, 2015-10-01 18:08:39]

https://chromiumcodereview.appspot.com/1368293012/diff/1/components/history/c...
File components/history/core/browser/history_service.h (right):

https://chromiumcodereview.appspot.com/1368293012/diff/1/components/history/c...
components/history/core/browser/history_service.h:507: bool
PostTaskAndReplyForTest(const base::Closure& task,
On 2015/09/30 23:52:10, sky wrote:
> THis is effectively duplicating what HistoryDBTask does. Can you use it
instead?

Didn't know about that one.  Converted.

[Scott Hess - ex-Googler, 2015-10-01 18:08:44]

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

[commit-bot: I haz the power, 2015-10-01 18:11:04]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1368293012/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1368293012/20001

[commit-bot: I haz the power, 2015-10-01 18:59:02]

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

[commit-bot: I haz the power, 2015-10-01 18:59:03]

Dry run: This issue passed the CQ dry run.

[engedy, 2015-10-01 22:15:41]

LGTM, thanks for taking care of this!

[sky, 2015-10-02 15:34:31]

LGTM

[Scott Hess - ex-Googler, 2015-10-02 17:41:49]

The CQ bit was checked by shess@chromium.org

[commit-bot: I haz the power, 2015-10-02 17:44:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1368293012/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1368293012/20001

[commit-bot: I haz the power, 2015-10-02 17:55:06]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-10-02 17:56:51]

Patchset 2 (id:??) landed as
https://crrev.com/f20e6bb6c89853231d3ad519456a1df000eaf3e4
Cr-Commit-Position: refs/heads/master@{#352073}