Add durable storage test for incognito.

Add durable storage test for incognito.

Incognito is not treated specially. But durability there is a no-op; web
storage only uses in memory databases in incognito so there's nothing to
protect from disk cleanup.

BUG=536613
Committed: https://crrev.com/8f17a6008008c2e2652d7acd62e4fc44a090c9ef
Cr-Commit-Position: refs/heads/master@{#351665}

[dgrogan, 2015-09-30 00:54:14]

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

[dgrogan, 2015-09-30 00:54:14]

Josh, could you review this?

[jsbell, 2015-09-30 20:47:37]

lgtm

https://chromiumcodereview.appspot.com/1382433002/diff/1/chrome/browser/stora...
File chrome/browser/storage/durable_storage_browsertest.cc (right):

https://chromiumcodereview.appspot.com/1382433002/diff/1/chrome/browser/stora...
chrome/browser/storage/durable_storage_browsertest.cc:1: // Copyright (c) 2012
The Chromium Authors. All rights reserved.
Should have been "Copyright 2015" from the get go :P

[dgrogan, 2015-09-30 21:48:32]

The CQ bit was checked by dgrogan@chromium.org

[dgrogan, 2015-09-30 21:48:32]

The patchset sent to the CQ was uploaded after l-g-t-m from jsbell@chromium.org
Link to the patchset: https://chromiumcodereview.appspot.com/1382433002/#ps20001
(title: "fix copyright year")

[commit-bot: I haz the power, 2015-09-30 21:49:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1382433002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1382433002/20001

[commit-bot: I haz the power, 2015-09-30 22:43:05]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-09-30 22:44:10]

Patchset 2 (id:??) landed as
https://crrev.com/8f17a6008008c2e2652d7acd62e4fc44a090c9ef
Cr-Commit-Position: refs/heads/master@{#351665}