Change preference APIs to take std::string instead of const char*.

base/prefs/scoped_user_pref_update.cc

 // Copyright 2013 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/scoped_user_pref_update.h"
 
 #include "base/logging.h"
 #include "base/prefs/pref_notifier.h"
 #include "base/prefs/pref_service.h"
 
 namespace subtle {
 
 ScopedUserPrefUpdateBase::ScopedUserPrefUpdateBase(PrefService* service,
-                                                   const char* path)
-    : service_(service),
-      path_(path),
-      value_(NULL) {
+                                                   const std::string& path)
+    : service_(service), path_(path), value_(NULL) {
   DCHECK(service_->CalledOnValidThread());
 }
 
 ScopedUserPrefUpdateBase::~ScopedUserPrefUpdateBase() {
   Notify();
 }
 
 base::Value* ScopedUserPrefUpdateBase::GetValueOfType(base::Value::Type type) {
   DCHECK(CalledOnValidThread());
   if (!value_)
     value_ = service_->GetMutableUserPref(path_.c_str(), type);
   return value_;
 }
 
 void ScopedUserPrefUpdateBase::Notify() {
   if (value_) {
     service_->ReportUserPrefChanged(path_);
     value_ = NULL;
   }
 }
 
 }  // namespace subtle