Fix outstanding request stats for multiple transfer navigations.

content/browser/loader/resource_dispatcher_host_impl.cc

Index: content/browser/loader/resource_dispatcher_host_impl.cc
diff --git a/content/browser/loader/resource_dispatcher_host_impl.cc b/content/browser/loader/resource_dispatcher_host_impl.cc
index a1cb1f1c15e8c7a0499e157d2e19c6ae16234193..64f71f01b290098983c62aabd7d1a76251ef6eeb 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -1004,10 +1004,12 @@ void ResourceDispatcherHostImpl::UpdateRequestForTransfer(
   GlobalRequestID new_request_id(child_id, request_id);
 
   // Clear out data that depends on |info| before updating it.
-  IncrementOutstandingRequestsMemory(-1, *info);
-  OustandingRequestsStats empty_stats = { 0, 0 };
-  OustandingRequestsStats old_stats = GetOutstandingRequestsStats(*info);
-  UpdateOutstandingRequestsStats(*info, empty_stats);
+  // We always need to move the memory stats to the new process.  In contrast,
+  // stats.num_requests is only sometimes tracked.
+  OustandingRequestsStats stats = IncrementOutstandingRequestsMemory(-1, *info);
+  bool should_update_count = stats.num_requests > 0;

[davidben, 2014/10/13 17:40:04]

Hrm. Is this the right criteria? OutstandingRequestsStats are tracked on a
per-child, so this is true if ARH has ever called
IncrementOutstandingRequestsCount on any response. Whereas this wants to check
if this particular request has ever seen an IncrementOutstandingRequestsCount.

Perhaps the ResourceRequestInfoImpl shouldn't be passed as const reference, so
you can set a flag there.

[Charlie Reis, 2014/10/14 23:54:12]

Oops-- you're totally right.  Awkward that we don't always increment the count,
but after a little digging I see that there's a reason.
Yeah...  I'm not thrilled with modifying the request info this way, but it does
seem like the most straightforward way to have both process-level counts and
know whether a particular request is affected.  New patch uploaded.

+  if (should_update_count)
+    IncrementOutstandingRequestsCount(-1, *info);
   pending_loaders_.erase(old_request_id);
 
   // ResourceHandlers should always get state related to the request from the
@@ -1020,8 +1022,9 @@ void ResourceDispatcherHostImpl::UpdateRequestForTransfer(
   // Update maps that used the old IDs, if necessary.  Some transfers in tests
   // do not actually use a different ID, so not all maps need to be updated.
   pending_loaders_[new_request_id] = loader;
-  UpdateOutstandingRequestsStats(*info, old_stats);
   IncrementOutstandingRequestsMemory(1, *info);
+  if (should_update_count)
+    IncrementOutstandingRequestsCount(1, *info);
   if (old_routing_id != new_routing_id) {
     if (blocked_loaders_map_.find(old_routing_id) !=
             blocked_loaders_map_.end()) {