Adding instrumentation to locate the source of jankiness.

sync/internal_api/http_bridge.cc

Index: sync/internal_api/http_bridge.cc
diff --git a/sync/internal_api/http_bridge.cc b/sync/internal_api/http_bridge.cc
index c9db173c4270331905a640c7a16bd059c9c935b3..ff5e4e2fabe4a43578afb50b8b1b067b1984eaee 100644
--- a/sync/internal_api/http_bridge.cc
+++ b/sync/internal_api/http_bridge.cc
@@ -5,6 +5,7 @@
 #include "sync/internal_api/public/http_bridge.h"
 
 #include "base/message_loop/message_loop.h"
+#include "base/profiler/scoped_profile.h"
 #include "base/strings/string_number_conversions.h"
 #include "net/base/load_flags.h"
 #include "net/base/net_errors.h"
@@ -344,6 +345,11 @@ void HttpBridge::DestroyURLFetcherOnIOThread(net::URLFetcher* fetcher) {
 }
 
 void HttpBridge::OnURLFetchComplete(const net::URLFetcher* source) {
+  // TODO(vadimt): Remove ScopedProfile below once crbug.com/422577 is fixed.
+  tracked_objects::ScopedProfile tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "422577 HttpBridge::OnURLFetchComplete"));
+
   DCHECK(network_task_runner_->BelongsToCurrentThread());
   base::AutoLock lock(fetch_state_lock_);
   if (fetch_state_.aborted)