Adding instrumentation to locate the source of jankiness.

components/signin/core/browser/about_signin_internals.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/signin/core/browser/about_signin_internals.h"
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/hash.h"
 #include "base/i18n/time_formatting.h"
@@ skipping 212 matching lines @@
 }
 
 void AboutSigninInternals::NotifyObservers() {
   // TODO(vadimt): Remove ScopedTracker below once crbug.com/422460 is fixed.
   tracked_objects::ScopedTracker tracking_profile(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
           "422460 AboutSigninInternals::NotifyObservers"));
 
   scoped_ptr<base::DictionaryValue> signin_status_value =
       signin_status_.ToValue(client_->GetProductVersion());
+
+  tracked_objects::ScopedTracker tracking_profile1(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "422460 AboutSigninInternals::NotifyObservers1"));
+
   FOR_EACH_OBSERVER(AboutSigninInternals::Observer,
                     signin_observers_,
                     OnSigninStateChanged(signin_status_value.get()));
 }
 
 scoped_ptr<base::DictionaryValue> AboutSigninInternals::GetSigninStatus() {
   return signin_status_.ToValue(client_->GetProductVersion()).Pass();
 }
 
 void AboutSigninInternals::OnAccessTokenRequested(
@@ skipping 255 matching lines @@
     std::sort(it->second.begin(), it->second.end(), TokenInfo::LessThan);
     const std::vector<TokenInfo*>& tokens = it->second;
     for (size_t i = 0; i < tokens.size(); ++i) {
       base::DictionaryValue* token_info = tokens[i]->ToValue();
       token_details->Append(token_info);
     }
   }
 
   return signin_status.Pass();
 }