ServiceWorker: SWProviderHost no longer have to retain SWVersions

ServiceWorker: SWProviderHost no longer have to retain SWVersions

This is a cleanup patch.

ServiceWorkerProviderHost owns ServiceWorkerRegistration and the registration
owns ServiceWorkerVersions, so the provider host doesn't need to hold them.

BUG=n/a
TEST=run_webkit_tests.py --debug http/tests/serviceworker/

Committed: https://crrev.com/9625999ae9ad6a144c04a120cbad1d4b195fb371
Cr-Commit-Position: refs/heads/master@{#294732}

[nhiroki, 2014-09-12 09:03:41]

Patchset #1 (id:1) has been deleted

[nhiroki, 2014-09-12 09:10:53]

nhiroki@chromium.org changed reviewers:
+ horo@chromium.org

[nhiroki, 2014-09-12 09:10:54]

Ptal, thanks!

[michaeln, 2014-09-12 21:52:14]

woohooo -108 + 7, lgtm

[nhiroki, 2014-09-13 04:36:31]

The CQ bit was checked by nhiroki@chromium.org

[commit-bot: I haz the power, 2014-09-13 04:38:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/563923005/20001

[commit-bot: I haz the power, 2014-09-13 05:16:49]

Committed patchset #1 (id:20001) as f8948a62c329086ddb3289b95b427d433ac25eec

[commit-bot: I haz the power, 2014-09-13 05:19:44]

Patchset 1 (id:??) landed as
https://crrev.com/9625999ae9ad6a144c04a120cbad1d4b195fb371
Cr-Commit-Position: refs/heads/master@{#294732}