Split ServiceWorkerRegisterJob into two classes.
Factor out ServiceWorkerRegisterJob and ServiceWorkerUnregisterJob.
Also, use hardcoded callbacks when possible. As the register job gets
more complex (e.g., when adding installation) it can be easy to lose
track of what callback is calling what when they are passed in as
arguments.
No new test, refactoring only change.
BUG=349337
TBR=jam
Review URL: https://codereview.chromium.org/
219243002
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261143 0039d316-1c4b-4281-b951-d872f2087c98