[net] Ensure aborted HostResolverImpl::Jobs release slots in the dispatcher.

net/base/host_resolver_impl.cc

Index: net/base/host_resolver_impl.cc
diff --git a/net/base/host_resolver_impl.cc b/net/base/host_resolver_impl.cc
index 1e4d757af05ed2d6934e28ae95bafdffc1b125bb..d7a23ded5d411963e9df66521a27ea75ec502f63 100644
--- a/net/base/host_resolver_impl.cc
+++ b/net/base/host_resolver_impl.cc
@@ -1572,8 +1572,10 @@ void HostResolverImpl::CancelRequest(RequestHandle req_handle) {
     // that Request could not have been cancelled, so job->num_active_requests()
     // could not be 0. Therefore, we are not in Job::CompleteRequests().
     RemoveJob(job);
-    if (job->is_running())
+    if (job->is_running()) {
+      dispatcher_.OnJobFinished();

[cbentzel, 2012/03/02 19:05:02]

Does the ordering here matter? It's different in the AbortAllJobs case. Perhaps
we should move it into a helper function or make it part of abort?

[szym, 2012/03/02 19:09:30]

I feel that the preferred order is Abort then dispatch. Although arguably since
Jobs cannot complete synchronously it might make more sense to dispatch then
Abort.

Most importantly, Abort could delete |this| and |dispatcher_|. In
AbortAllInProgressJobs we use a self-life check which we are forced to anyway
(since we are in a loop, and it is not safe to Abort a Job once we know we are
deleted, due to dependencies such as NetLog).

I am okay changing it to dispatch then Abort which would let us move the
self-check to the for loop condition.

       job->Abort();
+    }
     delete job;
   }
 }
@@ -1724,9 +1726,14 @@ void HostResolverImpl::AbortAllInProgressJobs() {
     }
   }
 
+  // Check if no dispatcher slots leaked out.
+  DCHECK_EQ(dispatcher_.num_running_jobs(), jobs_to_abort.size());
+
   // Then Abort them and dispatch new Jobs.
   for (size_t i = 0; i < jobs_to_abort.size(); ++i) {
     jobs_to_abort[i]->Abort();
+    if (!self)
+      break;  // |this| got destroyed in a request callback.
     dispatcher_.OnJobFinished();
   }
   STLDeleteElements(&jobs_to_abort);