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

base/prefs/pref_member.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.
 //
 // A helper class that stays in sync with a preference (bool, int, real,
 // string or filepath).  For example:
 //
 // class MyClass {
 //  public:
 //   MyClass(PrefService* prefs) {
@@ skipping 85 matching lines @@
     mutable bool is_managed_;
     mutable bool is_user_modifiable_;
 
     DISALLOW_COPY_AND_ASSIGN(Internal);
   };
 
   PrefMemberBase();
   virtual ~PrefMemberBase();
 
   // See PrefMember<> for description.
-  void Init(const char* pref_name, PrefService* prefs,
+  void Init(const std::string& pref_name,
+            PrefService* prefs,
             const NamedChangeCallback& observer);
-  void Init(const char* pref_name, PrefService* prefs);
+  void Init(const std::string& pref_name, PrefService* prefs);
 
   virtual void CreateInternal() const = 0;
 
   // See PrefMember<> for description.
   void Destroy();
 
   void MoveToThread(
       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
 
   // PrefObserver
@@ skipping 43 matching lines @@
 class PrefMember : public subtle::PrefMemberBase {
  public:
   // Defer initialization to an Init method so it's easy to make this class be
   // a member variable.
   PrefMember() {}
   virtual ~PrefMember() {}
 
   // Do the actual initialization of the class.  Use the two-parameter
   // version if you don't want any notifications of changes.  This
   // method should only be called on the UI thread.
-  void Init(const char* pref_name, PrefService* prefs,
+  void Init(const std::string& pref_name,
+            PrefService* prefs,
             const NamedChangeCallback& observer) {
     subtle::PrefMemberBase::Init(pref_name, prefs, observer);
   }
-  void Init(const char* pref_name, PrefService* prefs,
+  void Init(const std::string& pref_name,
+            PrefService* prefs,
             const base::Closure& observer) {
     subtle::PrefMemberBase::Init(
         pref_name, prefs,
         base::Bind(&PrefMemberBase::InvokeUnnamedCallback, observer));
   }
-  void Init(const char* pref_name, PrefService* prefs) {
+  void Init(const std::string& pref_name, PrefService* prefs) {
     subtle::PrefMemberBase::Init(pref_name, prefs);
   }
 
   // Unsubscribes the PrefMember from the PrefService. After calling this
   // function, the PrefMember may not be used any more on the UI thread.
   // Assuming |MoveToThread| was previously called, |GetValue|, |IsManaged|,
   // and |IsUserModifiable| can still be called from the other thread but
   // the results will no longer update from the PrefService.
   // This method should only be called on the UI thread.
   void Destroy() {
@@ skipping 152 matching lines @@
 
 typedef PrefMember<bool> BooleanPrefMember;
 typedef PrefMember<int> IntegerPrefMember;
 typedef PrefMember<double> DoublePrefMember;
 typedef PrefMember<std::string> StringPrefMember;
 typedef PrefMember<base::FilePath> FilePathPrefMember;
 // This preference member is expensive for large string arrays.
 typedef PrefMember<std::vector<std::string> > StringListPrefMember;
 
 #endif  // BASE_PREFS_PREF_MEMBER_H_