[Upstream] Force instantiation of BSKSF during unit tests

[Upstream] Force instantiation of BSKSF during unit tests

Call EnsureBrowserStateKeyedServiceFactoriesBuilt() during initialisation of
"chrome_ios_unittests" to ensure the BSKSF are correctly registered against
the DependencyManager before launching the tests.

Call ios::RegisterPathProvider() before running the tests so that they can
use the iOS specific paths by name.

BUG=468694
R=droger@chromium.org

Committed: https://crrev.com/b28a28e9dab905b80853424ec344aa1667b06285
Cr-Commit-Position: refs/heads/master@{#327461}

[sdefresne, 2015-04-29 08:48:23]

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

[commit-bot: I haz the power, 2015-04-29 08:49:01]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1111193002/1

[droger, 2015-04-29 09:00:27]

lgtm

[sdefresne, 2015-04-29 09:03:17]

The CQ bit was unchecked by sdefresne@chromium.org

[sdefresne, 2015-04-29 09:03:18]

The CQ bit was checked by sdefresne@chromium.org

[sdefresne, 2015-04-29 09:03:22]

The CQ bit was checked by sdefresne@chromium.org

[commit-bot: I haz the power, 2015-04-29 09:03:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1111193002/1

[commit-bot: I haz the power, 2015-04-29 09:55:15]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-29 09:56:08]

Patchset 1 (id:??) landed as
https://crrev.com/b28a28e9dab905b80853424ec344aa1667b06285
Cr-Commit-Position: refs/heads/master@{#327461}