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

base/prefs/pref_registry.h

 // 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.
 
 #ifndef BASE_PREFS_PREF_REGISTRY_H_
 #define BASE_PREFS_PREF_REGISTRY_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/prefs/base_prefs_export.h"
 #include "base/prefs/pref_value_map.h"
@@ skipping 23 matching lines @@
   // Gets the registered defaults.
   scoped_refptr<PrefStore> defaults();
 
   // Allows iteration over defaults.
   const_iterator begin() const;
   const_iterator end() const;
 
   // Changes the default value for a preference. Takes ownership of |value|.
   //
   // |pref_name| must be a previously registered preference.
-  void SetDefaultPrefValue(const char* pref_name, base::Value* value);
+  void SetDefaultPrefValue(const std::string& pref_name, base::Value* value);
 
  protected:
   friend class base::RefCounted<PrefRegistry>;
   virtual ~PrefRegistry();
 
   // Used by subclasses to register a default value for a preference.
-  void RegisterPreference(const char* path, base::Value* default_value);
+  void RegisterPreference(const std::string& path, base::Value* default_value);
 
   scoped_refptr<DefaultPrefStore> defaults_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PrefRegistry);
 };
 
 #endif  // BASE_PREFS_PREF_REGISTRY_H_