Force migrate all clients from multi-install back to single-install.

chrome/installer/util/master_preferences_constants.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/installer/util/master_preferences_constants.h"
 
 namespace installer {
 namespace master_preferences {
-  const char kChrome[] = "chrome";
   const char kCreateAllShortcuts[] = "create_all_shortcuts";
   const char kDisableLogging[] = "disable_logging";
   const char kDistroDict[] = "distribution";
   const char kDistroImportBookmarksPref[] = "import_bookmarks";
   const char kDistroImportBookmarksFromFilePref[] =
       "import_bookmarks_from_file";
   const char kDistroImportHistoryPref[] = "import_history";
   const char kDistroImportHomePagePref[] = "import_home_page";
   const char kDistroImportSearchPref[] = "import_search_engine";
   const char kDistroPingDelay[] = "ping_delay";
@@ skipping 19 matching lines @@
   const char kMsiProductId[] = "msi_product_id";
   const char kMultiInstall[] = "multi_install";
   const char kRequireEula[] = "require_eula";
   const char kSystemLevel[] = "system_level";
   const char kVerboseLogging[] = "verbose_logging";
   const char kExtensionsBlock[] = "extensions.settings";
   const char kAllowDowngrade[] = "allow_downgrade";
 
 }  // namespace master_preferences
 }  // namespace installer