Make sure keybindings removed don't come back during extension update.

chrome/browser/extensions/extension_prefs.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 "chrome/browser/extensions/extension_prefs.h"
 
 #include "base/command_line.h"
 #include "base/prefs/pref_notifier.h"
 #include "base/prefs/pref_service.h"
 #include "base/string_util.h"
@@ skipping 166 matching lines @@
 const char kPrefCreationFlags[] = "creation_flags";
 
 // A preference that indicates whether the extension was installed from the
 // Chrome Web Store.
 const char kPrefFromWebStore[] = "from_webstore";
 
 // A preference that indicates whether the extension was installed from a
 // mock App created from a bookmark.
 const char kPrefFromBookmark[] = "from_bookmark";
 
-// A prefrence that indicates whethere the extension was installed as
+// A preference that indicates whether the extension was installed as
 // default apps.
 const char kPrefWasInstalledByDefault[] = "was_installed_by_default";
 
 // A preference that contains any extension-controlled preferences.
 const char kPrefPreferences[] = "preferences";
 
 // A preference that contains any extension-controlled incognito preferences.
 const char kPrefIncognitoPreferences[] = "incognito_preferences";
 
 // A preference that contains any extension-controlled regular-only preferences.
@@ skipping 2050 matching lines @@
     is_enabled = initial_state == Extension::ENABLED;
   }
 
   extension_pref_value_map_->RegisterExtension(extension_id, install_time,
                                                is_enabled);
   content_settings_store_->RegisterExtension(extension_id, install_time,
                                              is_enabled);
 }
 
 }  // namespace extensions