Introduce incognito preference settings.

chrome/browser/prefs/pref_member.cc

 // Copyright (c) 2010 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 "chrome/browser/prefs/pref_member.h"
 
 #include "base/logging.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/common/notification_type.h"
 
 namespace subtle {
 
 PrefMemberBase::PrefMemberBase()
     : observer_(NULL),
       prefs_(NULL),
       is_synced_(false),
       setting_value_(false) {
 }
 
 PrefMemberBase::~PrefMemberBase() {
-  if (!pref_name_.empty())
+  if (prefs_ && !pref_name_.empty())
     prefs_->RemovePrefObserver(pref_name_.c_str(), this);
 }
 
 
 void PrefMemberBase::Init(const char* pref_name, PrefService* prefs,
                           NotificationObserver* observer) {
   DCHECK(pref_name);
   DCHECK(prefs);
   DCHECK(pref_name_.empty());  // Check that Init is only called once.
   observer_ = observer;
   prefs_ = prefs;
   pref_name_ = pref_name;
   DCHECK(!pref_name_.empty());
 
   // Add ourself as a pref observer so we can keep our local value in sync.
   prefs_->AddPrefObserver(pref_name, this);
 }
 
+void PrefMemberBase::Destroy() {
+  if (prefs_) {
+    prefs_->RemovePrefObserver(pref_name_.c_str(), this);
+    prefs_ = NULL;
+  }

[Dan Beam, 2016/06/17 21:56:15]

out of curiosity, could pref_name_.clear() be called here so that PrefMembers
could be later Init()ialized?

[battre, 2016/06/20 07:53:46]

I did not find anything subtle that would break.

[Dan Beam, 2016/06/21 22:50:41]

I think making Destroy() private and encouraging folks to use
unique_ptr<PrefMember> + reset() might be better.

+}
+
 bool PrefMemberBase::IsManaged() const {
   DCHECK(!pref_name_.empty());
   const PrefService::Preference* pref =
       prefs_->FindPreference(pref_name_.c_str());
   return pref && pref->IsManaged();
 }
 
 void PrefMemberBase::Observe(NotificationType type,
                              const NotificationSource& source,
                              const NotificationDetails& details) {
@@ skipping 73 matching lines @@
 FilePathPrefMember::~FilePathPrefMember() {
 }
 
 void FilePathPrefMember::UpdateValueFromPref() const {
   value_ = prefs()->GetFilePath(pref_name().c_str());
 }
 
 void FilePathPrefMember::UpdatePref(const FilePath& value) {
   prefs()->SetFilePath(pref_name().c_str(), value);
 }