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

base/prefs/pref_member.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_member.h"
 
 #include "base/callback.h"
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/prefs/pref_service.h"
 #include "base/value_conversions.h"
 
 using base::MessageLoopProxy;
 using base::SingleThreadTaskRunner;
 
 namespace subtle {
 
 PrefMemberBase::PrefMemberBase()
     : prefs_(NULL),
       setting_value_(false) {
 }
 
 PrefMemberBase::~PrefMemberBase() {
   Destroy();
 }
 
-void PrefMemberBase::Init(const char* pref_name,
+void PrefMemberBase::Init(const std::string& pref_name,
                           PrefService* prefs,
                           const NamedChangeCallback& observer) {
   observer_ = observer;
   Init(pref_name, prefs);
 }
 
-void PrefMemberBase::Init(const char* pref_name,
-                          PrefService* prefs) {
-  DCHECK(pref_name);
+void PrefMemberBase::Init(const std::string& pref_name, PrefService* prefs) {
   DCHECK(prefs);
   DCHECK(pref_name_.empty());  // Check that Init is only called once.
   prefs_ = prefs;
   pref_name_ = pref_name;
   // Check that the preference is registered.
   DCHECK(prefs_->FindPreference(pref_name_.c_str()))

[gab, 2014/12/01 21:13:01]

Once again, another example, picked at random while looking around, of a place
where changing the API wasn't sufficient as the impl still uses c_str() to pass
things around which will force re-conversions with your new API, i.e.:

Previously: |pref_name_| was passed down this low-level API as a pointer,
potentially without being promoted to a string.
Now: You are guaranteed to force |pref_name_| into a c_str() every time this is
called.

Fixing at least base/prefs to use its own API properly seems worthwhile (then
fixing external callers is harder as mentioned above).

[Georges Khalil, 2014/12/02 17:57:00]

Done.

       << pref_name << " not registered.";
 
   // Add ourselves as a pref observer so we can keep our local value in sync.
   prefs_->AddPrefObserver(pref_name, this);
 }
 
 void PrefMemberBase::Destroy() {
   if (prefs_ && !pref_name_.empty()) {
     prefs_->RemovePrefObserver(pref_name_.c_str(), this);
     prefs_ = NULL;
@@ skipping 165 matching lines @@
   base::ListValue list_value;
   list_value.AppendStrings(value);
   prefs()->Set(pref_name().c_str(), list_value);
 }
 
 template <>
 bool PrefMember<std::vector<std::string> >::Internal::UpdateValueInternal(
     const base::Value& value) const {
   return subtle::PrefMemberVectorStringUpdate(value, &value_);
 }