Add an instrumentation in ServiceWorkerRegistration

We have a hypothesis that ServiceWorkerRegistration could be
destructed between ActivateWaitingVersion() and
ContinueActivation(). This CL adds an instrumentation to confirm
the hypothesis.

Bug: 1159778
Change-Id: Id15e4832e6ce82cc5230dc3f907b3e90036e62de
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2636007Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Kenichi Ishibashi <bashi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844704}

content/browser/service_worker/service_worker_registration.cc

@@ -67,6 +67,12 @@ ServiceWorkerRegistration::ServiceWorkerRegistration(
 ServiceWorkerRegistration::~ServiceWorkerRegistration() {
   DCHECK_CURRENTLY_ON(ServiceWorkerContext::GetCoreThreadId());
   DCHECK(!listeners_.might_have_observers());
+
+  // TODO(crbug.com/1159778): Remove once the bug is fixed.
+  CHECK(!in_activate_waiting_version_)
+      << "ServiceWorkerRegistration was destroyed while activating waiting "
+         "version";
+
   if (context_)
     context_->RemoveLiveRegistration(registration_id_);
 }
@@ -480,6 +486,8 @@ void ServiceWorkerRegistration::ActivateWaitingVersion(bool delay) {
   if (activating_version->is_redundant())
     return;  // Activation is no longer relevant.
 
+  in_activate_waiting_version_ = true;
+
   // "5. If exitingWorker is not null,
   if (exiting_version.get()) {
     // Whenever activation happens, evict bfcached controllees.
@@ -517,6 +525,7 @@ void ServiceWorkerRegistration::ActivateWaitingVersion(bool delay) {
   // "10. Queue a task to fire an event named activate..."
   // The browser could be shutting down. To avoid spurious start worker
   // failures, wait a bit before continuing.
+  in_activate_waiting_version_ = false;
   if (delay) {
     task_runner_->PostDelayedTask(
         FROM_HERE,

content/browser/service_worker/service_worker_registration.h

@@ -286,6 +286,9 @@ class CONTENT_EXPORT ServiceWorkerRegistration
   // longer considered a lame duck.
   base::RepeatingTimer lame_duck_timer_;
 
+  // TODO(crbug.com/1159778): Remove once the bug is fixed.
+  bool in_activate_waiting_version_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(ServiceWorkerRegistration);
 };