[sql] Patch SQLite to allow control of close-time WAL checkpoint.

[sql] Patch SQLite to allow control of close-time WAL checkpoint.

SQLite WAL mode by default checkpoints the WAL to the main database at
close time.  Chromium closes databases at shutdown, which causes
shutdown slowdowns due to buffered data being flushed.  WAL
checkpointing would effectively increase the amount of buffered data
being flushed.

[WAL mode is currently not in use by Chromium.]

BUG=675264

[Scott Hess - ex-Googler, 2016-12-17 00:03:37]

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

[commit-bot: I haz the power, 2016-12-17 00:04:50]

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, 2016-12-17 01:50:00]

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

[commit-bot: I haz the power, 2016-12-17 01:50:01]

Dry run: This issue passed the CQ dry run.

[Scott Hess - ex-Googler, 2016-12-17 02:18:47]

fix UsesUsleep comment from trybot results

[Scott Hess - ex-Googler, 2016-12-17 02:19:53]

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

[Scott Hess - ex-Googler, 2016-12-17 02:19:53]

I'm going to start posting some infrastructure changes to get WAL mode working
in tests.  I asked about checkpointing on close on the sqlite-users mailing
list, and was pointed at a patch to the pending release of SQLite, so seems
legit.

[Scott Hess - ex-Googler, 2017-04-18 23:15:32]

Description was changed from

==========
[sql] Patch SQLite to allow control of close-time WAL checkpoint.

SQLite WAL mode by default checkpoints the WAL to the main database at
close time.  Chromium closes databases at shutdown, which causes
shutdown slowdowns due to buffered data being flushed.  WAL
checkpointing would effectively increase the amount of buffered data
being flushed.

[WAL mode is currently not in use by Chromium.]

BUG=675264
==========

to

==========
[sql] Patch SQLite to allow control of close-time WAL checkpoint.

SQLite WAL mode by default checkpoints the WAL to the main database at
close time.  Chromium closes databases at shutdown, which causes
shutdown slowdowns due to buffered data being flushed.  WAL
checkpointing would effectively increase the amount of buffered data
being flushed.

[WAL mode is currently not in use by Chromium.]

BUG=675264
==========