Add tracing to prefs for analyzing startup performance

chrome/browser/prefs/pref_service_syncable_builder.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 "chrome/browser/prefs/pref_service_syncable_builder.h"
 
+#include "base/debug/trace_event.h"
 #include "base/prefs/default_pref_store.h"
 #include "base/prefs/pref_notifier_impl.h"
 #include "base/prefs/pref_value_store.h"
 #include "chrome/browser/policy/configuration_policy_pref_store.h"
 #include "chrome/browser/policy/policy_service.h"
 #include "chrome/browser/prefs/command_line_pref_store.h"
 #include "chrome/browser/prefs/pref_service_syncable.h"
 #include "components/user_prefs/pref_registry_syncable.h"
 
 PrefServiceSyncableBuilder::PrefServiceSyncableBuilder() {
@@ skipping 19 matching lines @@
 #endif
 
 PrefServiceSyncableBuilder&
 PrefServiceSyncableBuilder::WithCommandLine(CommandLine* command_line) {
   WithCommandLinePrefs(new CommandLinePrefStore(command_line));
   return *this;
 }
 
 PrefServiceSyncable* PrefServiceSyncableBuilder::CreateSyncable(
     user_prefs::PrefRegistrySyncable* pref_registry) {
+  TRACE_EVENT0("browser", "PrefServiceSyncableBuilder::CreateSyncable")
   PrefNotifierImpl* pref_notifier = new PrefNotifierImpl();
   PrefServiceSyncable* pref_service = new PrefServiceSyncable(
       pref_notifier,
       new PrefValueStore(
           managed_prefs_.get(),
           extension_prefs_.get(),
           command_line_prefs_.get(),
           user_prefs_.get(),
           recommended_prefs_.get(),
           pref_registry->defaults(),
           pref_notifier),
       user_prefs_.get(),
       pref_registry,
       read_error_callback_,
       async_);
   ResetDefaultState();
   return pref_service;
 }