IndexedDB: Revert change to enable reuse of leveldb manifest in IDB.

IndexedDB: Revert change to enable reuse of leveldb manifest in IDB.

The developer channel was showing spikes in %error when opening a leveldb. These
spikes were between 0-10x the normal rates of errors.

This change is a manual revert of #308493 (ddd0184).

BUG=402980, 395799
Committed: https://crrev.com/ca6c87548326305bcced69aef5dd3fc41c0564ef
Cr-Commit-Position: refs/heads/master@{#310338}

[cmumford, 2015-01-07 17:27:26]

cmumford@chromium.org changed reviewers:
+ dgrogan@chromium.org, jsbell@chromium.org

[cmumford, 2015-01-07 17:27:27]

Will take the first lgtm.

Branch is in two days so reverting before then :-(

The original change (#308493) landed on 12/15, and the numbers started to spike
in dev channel on 12/20. It's also possible that it's the roll to leveldb 1.18
(#307976) which landed on 12/11, but this is more likely.

[jsbell, 2015-01-07 17:28:23]

lgtm

[cmumford, 2015-01-07 17:33:43]

The CQ bit was checked by cmumford@chromium.org

[commit-bot: I haz the power, 2015-01-07 17:34:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/841753003/1

[commit-bot: I haz the power, 2015-01-07 19:39:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-07 19:39:47]

Patchset 1 (id:??) landed as
https://crrev.com/ca6c87548326305bcced69aef5dd3fc41c0564ef
Cr-Commit-Position: refs/heads/master@{#310338}