commit 26f26cd82a8159dff52fdef10b0a7ebb84c48040
author Han Leon <leon.han@intel.com> Sat Jun 23 22:45:06 2018
committer Commit Bot <commit-bot@chromium.org> Sat Jun 23 22:45:06 2018
tree 199c2e52fdc779ae95466535072cb1eaebc30f37
parent 20190791026106431288bb521870e9ec5ff00622

[ServiceWorker] Avoid using stale pointer of EmbeddedWorkerInstance

We're saving the raw pointer of an EmbeddedWorkerInstance in a
base::ScopedObserver member of ServiceWorkerRegisterJob, but, the
EmbeddedWorkerInstance is not guaranteed to outlive the
ServiceWorkerRegisterJob, it may get destroyed and lead to a situation
that ServiceWorkerRegisterJob holds a stale pointer, which could lead
to crash.

This CL lets ServiceWorkerRegisterJob listen OnDetached() from the
EmbeddedWorkerInstance so it can be aware that the EmbeddedWorkerInstanc
pointer is going to be stale and should be removed from the source list
of base::ScopedObserver.

This fix should be safe enough now, but in longer term we'll try to
remove EmbeddedWorkerInstance::Listener interface and let
EmbeddedWorkerInstance talk directly to its owner ServiceWorkerVersion,
then let ServiceWorkerRegisterJob observe the ServiceWorkerVersion it's
manipulating to get OnScriptLoaded() notification.

BUG=854063,855394

Change-Id: I9c5a46beda1aafff32a86b9055be2b53d50fda97
Reviewed-on: https://chromium-review.googlesource.com/1112904
Commit-Queue: Han Leon <leon.han@intel.com>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569906}