Update from https://crrev.com/306655

base/prefs/pref_notifier_impl.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 "base/prefs/pref_notifier_impl.h"
 
 #include "base/logging.h"
 #include "base/prefs/pref_service.h"
 #include "base/stl_util.h"
 
@@ skipping 20 matching lines @@
   // Same for initialization observers.
   if (!init_observers_.empty())
     LOG(WARNING) << "Init observer found at shutdown.";
 
   STLDeleteContainerPairSecondPointers(pref_observers_.begin(),
                                        pref_observers_.end());
   pref_observers_.clear();
   init_observers_.clear();
 }
 
-void PrefNotifierImpl::AddPrefObserver(const char* path,
+void PrefNotifierImpl::AddPrefObserver(const std::string& path,
                                        PrefObserver* obs) {
   // Get the pref observer list associated with the path.
   PrefObserverList* observer_list = NULL;
   const PrefObserverMap::iterator observer_iterator =
       pref_observers_.find(path);
   if (observer_iterator == pref_observers_.end()) {
     observer_list = new PrefObserverList;
     pref_observers_[path] = observer_list;
   } else {
     observer_list = observer_iterator->second;
   }
 
   // Add the pref observer. ObserverList will DCHECK if it already is
   // in the list.
   observer_list->AddObserver(obs);
 }
 
-void PrefNotifierImpl::RemovePrefObserver(const char* path,
+void PrefNotifierImpl::RemovePrefObserver(const std::string& path,
                                           PrefObserver* obs) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   const PrefObserverMap::iterator observer_iterator =
       pref_observers_.find(path);
   if (observer_iterator == pref_observers_.end()) {
     return;
   }
 
   PrefObserverList* observer_list = observer_iterator->second;
@@ skipping 21 matching lines @@
        it != observers.end();
        ++it) {
     it->Run(succeeded);
   }
 }
 
 void PrefNotifierImpl::FireObservers(const std::string& path) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   // Only send notifications for registered preferences.
-  if (!pref_service_->FindPreference(path.c_str()))
+  if (!pref_service_->FindPreference(path))
     return;
 
   const PrefObserverMap::iterator observer_iterator =
       pref_observers_.find(path);
   if (observer_iterator == pref_observers_.end())
     return;
 
   FOR_EACH_OBSERVER(PrefObserver,
                     *(observer_iterator->second),
                     OnPreferenceChanged(pref_service_, path));
 }
 
 void PrefNotifierImpl::SetPrefService(PrefService* pref_service) {
   DCHECK(pref_service_ == NULL);
   pref_service_ = pref_service;
 }