Adding instrumentation to locate the source of jankiness.

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 fa9c0442eab427857bb35e2af52400fbc225d749..f8264c229c7e8af58246fba763a53568dcf99791 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -21,6 +21,7 @@
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/sparse_histogram.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/stl_util.h"
 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
 #include "content/browser/appcache/appcache_interceptor.h"
@@ -2151,6 +2152,11 @@ void LoadInfoUpdateCallback(const LoadInfoMap& info_map) {
 }  // namespace
 
 void ResourceDispatcherHostImpl::UpdateLoadStates() {
+  // TODO(pkasting): Remove ScopedTracker below once crbug.com/455952 is
+  // fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "455952 ResourceDispatcherHostImpl::UpdateLoadStates"));
   // Populate this map with load state changes, and then send them on to the UI
   // thread where they can be passed along to the respective RVHs.
   LoadInfoMap info_map;