Switch ObserverList::size() to ObserverList::might_have_observers() Pt.1

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 d4f6e534432ab08c44ba4559dc2d4dade8779584..2a4ad9ac684eaf013e8717688027dc894c13aa1b 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -1813,7 +1813,7 @@ void ResourceDispatcherHostImpl::UnregisterResourceMessageDelegate(
   DelegateMap::iterator it = delegate_map_.find(id);
   DCHECK(it->second->HasObserver(delegate));
   it->second->RemoveObserver(delegate);
-  if (it->second->size() == 0) {
+  if (!it->second->might_have_observers()) {
     delete it->second;
     delegate_map_.erase(it);
   }