Revert "Fix masters_test presubmit_tests by using serialized sqlite access."

Revert 4e7e4672aae819f312c9691544652f251964007f to make multiple connections to sqlite databases again.

This is safe after https://codereview.chromium.org/2103053002/

BUG=620572
Committed: https://chromium.googlesource.com/chromium/tools/build/+/312d2566bfcb38bcaa25e93c27d9d862d05c7a8a

[dsansome, 2016-06-28 08:58:21]

Description was changed from

==========
Revert "Fix masters_test presubmit_tests by using serialized sqlite access."

This reverts commit 4e7e4672aae819f312c9691544652f251964007f.

BUG=
==========

to

==========
Revert 4e7e4672aae819f312c9691544652f251964007f to make multiple connections to
sqlite databases again.

This is safe after https://codereview.chromium.org/2103053002/

BUG=620572
==========

[dsansome, 2016-06-28 08:58:39]

dsansome@chromium.org changed reviewers:
+ stip@chromium.org

[ghost stip (do not use), 2016-07-01 01:30:52]

lgtm

[dsansome, 2016-07-01 04:52:42]

The CQ bit was checked by dsansome@chromium.org

[commit-bot: I haz the power, 2016-07-01 04:52:52]

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, 2016-07-01 04:56:49]

Description was changed from

==========
Revert 4e7e4672aae819f312c9691544652f251964007f to make multiple connections to
sqlite databases again.

This is safe after https://codereview.chromium.org/2103053002/

BUG=620572
==========

to

==========
Revert 4e7e4672aae819f312c9691544652f251964007f to make multiple connections to
sqlite databases again.

This is safe after https://codereview.chromium.org/2103053002/

BUG=620572

Committed:
https://chromium.googlesource.com/chromium/tools/build/+/312d2566bfcb38bcaa25...
==========

[commit-bot: I haz the power, 2016-07-01 04:56:50]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/tools/build/+/312d2566bfcb38bcaa25...

[ghost stip (do not use), 2016-07-07 16:33:59]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2126033003/ by stip@chromium.org.

The reason for reverting is: possible cause of
https://bugs.chromium.org/p/chromium/issues/detail?id=626354.