Push API: Don't unsubscribe when finding Service Worker fails

Push API: Don't unsubscribe when finding Service Worker fails

Failing to find a service worker might be temporary, so we shouldn't
unsubscribe in this case. Continue to unsubscribe if the Service Worker
is actually not found (e.g. because it has been unregistered).

Also adds more UMA in this area.

BUG=642139
Committed: https://crrev.com/983872d32d2b818957e3ba7714b7a822a27e0dd8
Cr-Commit-Position: refs/heads/master@{#420447}

[johnme, 2016-09-22 17:29:45]

johnme@chromium.org changed reviewers:
+ peter@chromium.org

[Peter Beverloo, 2016-09-22 17:37:23]

lgtm

[johnme, 2016-09-22 17:42:13]

johnme@chromium.org changed reviewers:
+ isherman@chromium.org

[Ilya Sherman, 2016-09-22 18:43:54]

histograms lgtm

[johnme, 2016-09-22 19:23:00]

The CQ bit was checked by johnme@chromium.org

[commit-bot: I haz the power, 2016-09-22 19:23:23]

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, 2016-09-22 20:39:45]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-22 20:43:32]

Description was changed from

==========
Push API: Don't unsubscribe when finding Service Worker fails

Failing to find a service worker might be temporary, so we shouldn't
unsubscribe in this case. Continue to unsubscribe if the Service Worker
is actually not found (e.g. because it has been unregistered).

Also adds more UMA in this area.

BUG=642139
==========

to

==========
Push API: Don't unsubscribe when finding Service Worker fails

Failing to find a service worker might be temporary, so we shouldn't
unsubscribe in this case. Continue to unsubscribe if the Service Worker
is actually not found (e.g. because it has been unregistered).

Also adds more UMA in this area.

BUG=642139

Committed: https://crrev.com/983872d32d2b818957e3ba7714b7a822a27e0dd8
Cr-Commit-Position: refs/heads/master@{#420447}
==========

[commit-bot: I haz the power, 2016-09-22 20:43:33]

Patchset 1 (id:??) landed as
https://crrev.com/983872d32d2b818957e3ba7714b7a822a27e0dd8
Cr-Commit-Position: refs/heads/master@{#420447}