Add more per-tab preferences.

chrome/browser/prefs/pref_service.h

 // Copyright (c) 2011 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.
 
 // This provides a way to access the application's current preferences.
 
 #ifndef CHROME_BROWSER_PREFS_PREF_SERVICE_H_
 #define CHROME_BROWSER_PREFS_PREF_SERVICE_H_
 #pragma once
 
@@ skipping 220 matching lines @@
                                     PrefSyncStatus sync_status);
   void RegisterLocalizedDoublePref(const char* path,
                                    int locale_default_message_id,
                                    PrefSyncStatus sync_status);
   void RegisterLocalizedStringPref(const char* path,
                                    int locale_default_message_id,
                                    PrefSyncStatus sync_status);
   void RegisterInt64Pref(const char* path,
                          int64 default_value,
                          PrefSyncStatus sync_status);
+  // Unregisters a preference.
+  void UnregisterPreference(const char* path);
 
   // If the path is valid and the value at the end of the path matches the type
   // specified, it will return the specified value.  Otherwise, the default
   // value (set when the pref was registered) will be returned.
   bool GetBoolean(const char* path) const;
   int GetInteger(const char* path) const;
   double GetDouble(const char* path) const;
   std::string GetString(const char* path) const;
   FilePath GetFilePath(const char* path) const;
 
@@ skipping 134 matching lines @@
   // of registered preferences are.
   mutable PreferenceSet prefs_;
 
   // The model associator that maintains the links with the sync db.
   scoped_ptr<PrefModelAssociator> pref_sync_associator_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefService);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_SERVICE_H_