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

base/prefs/pref_value_store_unittest.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 <string>
 
 #include "base/bind.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/prefs/pref_notifier.h"
@@ skipping 219 matching lines @@
         prefs::kUserPref,
         default_pref::kUserValue);
     default_pref_store_->SetString(
         prefs::kRecommendedPref,
         default_pref::kRecommendedValue);
     default_pref_store_->SetString(
         prefs::kDefaultPref,
         default_pref::kDefaultValue);
   }
 
-  void ExpectValueChangeNotifications(const char* name) {
+  void ExpectValueChangeNotifications(const std::string& name) {
     EXPECT_CALL(pref_notifier_, OnPreferenceChanged(name));
     EXPECT_CALL(*sync_associator_, ProcessPrefChange(name));
   }
 
   void CheckAndClearValueChangeNotifications() {
     Mock::VerifyAndClearExpectations(&pref_notifier_);
     Mock::VerifyAndClearExpectations(sync_associator_.get());
   }
 
   MockPrefNotifier pref_notifier_;
@@ skipping 410 matching lines @@
       prefs::kCommandLinePref));
   EXPECT_TRUE(pref_value_store_->PrefValueExtensionModifiable(
       prefs::kUserPref));
   EXPECT_TRUE(pref_value_store_->PrefValueExtensionModifiable(
       prefs::kRecommendedPref));
   EXPECT_TRUE(pref_value_store_->PrefValueExtensionModifiable(
       prefs::kDefaultPref));
   EXPECT_TRUE(pref_value_store_->PrefValueExtensionModifiable(
       prefs::kMissingPref));
 }