Guarantees ServiceWorkerCacheStorage callbacks are called.

Guarantees ServiceWorkerCacheStorage callbacks are called by making the callback functions static and passing a WeakPtr to the ServiceWorkerCacheStorage where necessary.

Part of the following CL chain to guarantee callbacks are called throughout ServiceWorkerCacheStorage:

1. Guarantee CacheLoader callbacks: https://codereview.chromium.org/504233003/
2. Guarantee LazyInit callbacks: https://codereview.chromium.org/512743002/
* 3. Guarantee Create/Delete callbacks: https://codereview.chromium.org/511893002/
4. Reorganize the methods: https://codereview.chromium.org/510813002/


BUG=392621

[jkarlin, 2014-08-27 14:24:25]

Patchset #3 (id:40001) has been deleted

[jkarlin, 2014-08-27 14:24:31]

Patchset #2 (id:20001) has been deleted

[jkarlin, 2014-08-27 14:24:38]

Patchset #1 (id:1) has been deleted

[jkarlin, 2014-08-27 14:47:47]

jkarlin@chromium.org changed reviewers:
+ michaeln@chromium.org

[jkarlin, 2014-08-27 14:47:47]

michaeln: Please review all.  Thanks!

[jkarlin, 2014-08-27 16:12:17]

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

[jkarlin, 2014-08-27 16:15:23]

On 2014/08/27 16:12:17, jkarlin wrote:
> mailto:jkarlin@chromium.org changed reviewers:
> + mailto:horo@chromium.org

horo + michaeln: Please review all, thanks!

[jkarlin, 2014-08-28 11:03:28]

jkarlin@chromium.org changed reviewers:
- horo@chromium.org, michaeln@chromium.org

[jkarlin, 2014-08-28 11:05:24]

On 2014/08/28 11:03:28, jkarlin wrote:
> mailto:jkarlin@chromium.org changed reviewers:
> - mailto:horo@chromium.org, mailto:michaeln@chromium.org

Removed reviewers as this patch isn't required and adds complexity.