Revert of Revert of Reland: Optimizes IndexedDB's DeleteDatabase when no db exists

Revert of Revert of Reland: Optimizes IndexedDB's DeleteDatabase when no db exists (patchset #1 id:1 of https://codereview.chromium.org/1225513002/)

Reason for revert:
Test is still flaky.

Original issue's description:
> Revert of Reland: Optimizes IndexedDB's DeleteDatabase when no db exists (patchset #1 id:1 of https://codereview.chromium.org/1216573008/)
>
> Reason for revert:
> Some bots still flaky. See crbug.com/506467
>
> Original issue's description:
> > Reland: Optimizes IndexedDB's DeleteDatabase when no db exists
> >
> > When deleting the non existing database in a origin with no existing
> > backing store, then in DeleteDatabse(), early exiting before
> > OpenBackingStore, so that it wont results in multiple transaction as
> > earlier.
> >
> > Original patch by: payal.pandey
> >
> > This was reverted (see crrev.com/1071553002) when it appeared to make
> > a test flaky, but the test continues to flake (now tracked as
> > crbug.com/505609) so let's try relanding.
> >
> > BUG=460236
> >
> > Committed: https://crrev.com/4cbc8f1b383fb8145056295176912d53030a98b0
> > Cr-Commit-Position: refs/heads/master@{#336796}
>
> TBR=cmumford@chromium.org,jsbell@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=460236
>
> Committed: https://crrev.com/4e132285cadc8875bd8bf5d0078f325562fdd620
> Cr-Commit-Position: refs/heads/master@{#337228}

TBR=cmumford@chromium.org,jsbell@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=460236
Committed: https://crrev.com/44ca3fcacc30b7f0a112810f3c98e800eed6dfab
Cr-Commit-Position: refs/heads/master@{#337231}

[vkuzkokov, 2015-07-02 16:51:59]

Created Revert of Revert of Reland: Optimizes IndexedDB's DeleteDatabase when no
db exists

[commit-bot: I haz the power, 2015-07-02 16:52:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1224533004/1

[commit-bot: I haz the power, 2015-07-02 16:53:07]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-02 16:53:58]

Patchset 1 (id:??) landed as
https://crrev.com/44ca3fcacc30b7f0a112810f3c98e800eed6dfab
Cr-Commit-Position: refs/heads/master@{#337231}