Fix crash when forwarding a request to a null service worker.

Fix crash when forwarding a request to a null service worker.

This crash occurred when a ServiceWorkerControlleeRequestHandler was
created to handle a subresource request for a provider host with a
controller, but by the time MaybeCreateJob() was created the controller
and active version was removed due to
ServiceWorkerRegistration::DeleteVersion().

In this case, we just tell the URLRequestJob to abort with error rather
than handle the error (e.g., by fall back to network). We don't want to
silently hide the exceptional case in case some bug makes this happen
often.

Also add some general comments and DCHECKs in ServiceWorkerProviderHost
to clarify controller vs active version.

BUG=655910
Committed: https://crrev.com/ba53250ca4a45cc39c9381ad3bfaa990532aaa78
Cr-Commit-Position: refs/heads/master@{#440742}

[falken, 2016-12-27 05:53:05]

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

[falken, 2016-12-27 05:53:06]

nhiroki: ptal
horo: FYI

Added a unit test but I'm not sure how to test this manually in Chrome itself.

[falken, 2016-12-27 05:53:16]

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

[commit-bot: I haz the power, 2016-12-27 05:53:28]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[falken, 2016-12-27 06:50:58]

OK I managed to test manually by forcing a lost controller for some subresources
and fixed some issues. PTAL.

[falken, 2016-12-27 06:51:35]

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

[commit-bot: I haz the power, 2016-12-27 06:51:47]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[nhiroki, 2016-12-27 08:20:01]

lgtm

[falken, 2016-12-27 08:25:41]

The CQ bit was unchecked by falken@chromium.org

[falken, 2016-12-27 08:25:42]

The CQ bit was checked by falken@chromium.org

[falken, 2016-12-27 08:25:43]

The CQ bit was unchecked by falken@chromium.org

[falken, 2016-12-27 08:25:49]

The CQ bit was checked by falken@chromium.org

[commit-bot: I haz the power, 2016-12-27 08:25:57]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-12-27 08:44:04]

CQ is committing da patch.

Bot data: {"patchset_id": 60001, "attempt_start_ts": 1482827149003650,
"parent_rev": "b9fdd8e40ce74d3c1ee96be538bcdcc0bc7cb099", "commit_rev":
"588387398166927ae34dd5ae97c15f171adcd683"}

[commit-bot: I haz the power, 2016-12-27 08:44:37]

Description was changed from

==========
Fix crash when forwarding a request to a null service worker.

This crash occurred when a ServiceWorkerControlleeRequestHandler was
created to handle a subresource request for a provider host with a
controller, but by the time MaybeCreateJob() was created the controller
and active version was removed due to
ServiceWorkerRegistration::DeleteVersion().

In this case, we just tell the URLRequestJob to abort with error rather
than handle the error (e.g., by fall back to network). We don't want to
silently hide the exceptional case in case some bug makes this happen
often.

Also add some general comments and DCHECKs in ServiceWorkerProviderHost
to clarify controller vs active version.

BUG=655910
==========

to

==========
Fix crash when forwarding a request to a null service worker.

This crash occurred when a ServiceWorkerControlleeRequestHandler was
created to handle a subresource request for a provider host with a
controller, but by the time MaybeCreateJob() was created the controller
and active version was removed due to
ServiceWorkerRegistration::DeleteVersion().

In this case, we just tell the URLRequestJob to abort with error rather
than handle the error (e.g., by fall back to network). We don't want to
silently hide the exceptional case in case some bug makes this happen
often.

Also add some general comments and DCHECKs in ServiceWorkerProviderHost
to clarify controller vs active version.

BUG=655910

Review-Url: https://codereview.chromium.org/2604763002
==========

[commit-bot: I haz the power, 2016-12-27 08:44:38]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2017-01-02 15:45:50]

Description was changed from

==========
Fix crash when forwarding a request to a null service worker.

This crash occurred when a ServiceWorkerControlleeRequestHandler was
created to handle a subresource request for a provider host with a
controller, but by the time MaybeCreateJob() was created the controller
and active version was removed due to
ServiceWorkerRegistration::DeleteVersion().

In this case, we just tell the URLRequestJob to abort with error rather
than handle the error (e.g., by fall back to network). We don't want to
silently hide the exceptional case in case some bug makes this happen
often.

Also add some general comments and DCHECKs in ServiceWorkerProviderHost
to clarify controller vs active version.

BUG=655910

Review-Url: https://codereview.chromium.org/2604763002
==========

to

==========
Fix crash when forwarding a request to a null service worker.

This crash occurred when a ServiceWorkerControlleeRequestHandler was
created to handle a subresource request for a provider host with a
controller, but by the time MaybeCreateJob() was created the controller
and active version was removed due to
ServiceWorkerRegistration::DeleteVersion().

In this case, we just tell the URLRequestJob to abort with error rather
than handle the error (e.g., by fall back to network). We don't want to
silently hide the exceptional case in case some bug makes this happen
often.

Also add some general comments and DCHECKs in ServiceWorkerProviderHost
to clarify controller vs active version.

BUG=655910

Committed: https://crrev.com/ba53250ca4a45cc39c9381ad3bfaa990532aaa78
Cr-Commit-Position: refs/heads/master@{#440742}
==========

[commit-bot: I haz the power, 2017-01-02 15:45:51]

Patchset 4 (id:??) landed as
https://crrev.com/ba53250ca4a45cc39c9381ad3bfaa990532aaa78
Cr-Commit-Position: refs/heads/master@{#440742}