Add support for --critical-update-version to installer.

chrome/installer/setup/setup_main.cc

 // 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.
 
 #include <windows.h>
 #include <msi.h>
 #include <shellapi.h>
 #include <shlobj.h>
 
 #include <string>
@@ skipping 212 matching lines @@
   // First, add the multi-install binaries, if relevant.
   if (installer_state->is_multi_install())
     dists[num_dists++] = installer_state->multi_package_binaries_distribution();
   // Next, add all products we're operating on.  std::transform can handily do
   // this for us, but this is discouraged as being too tricky.
   const Products& products = installer_state->products();
   for (Products::size_type i = 0; i < products.size(); ++i) {
     dists[num_dists++] = products[i]->distribution();
   }
 
-  // Add work items to delete the "opv" and "cmd" values from all distributions.
+  // Add work items to delete the "opv", "cpv", and "cmd" values from all
+  // distributions.
   HKEY reg_root = installer_state->root_key();
   std::wstring version_key;
   for (int i = 0; i < num_dists; ++i) {
     version_key = dists[i]->GetVersionKey();
-    install_list->AddDeleteRegValueWorkItem(reg_root,
-                                            version_key,
-                                            google_update::kRegOldVersionField);
-    install_list->AddDeleteRegValueWorkItem(reg_root,
-                                            version_key,
-                                            google_update::kRegRenameCmdField);
+    install_list->AddDeleteRegValueWorkItem(
+        reg_root, version_key, google_update::kRegOldVersionField);
+    install_list->AddDeleteRegValueWorkItem(
+        reg_root, version_key, google_update::kRegCriticalVersionField);
+    install_list->AddDeleteRegValueWorkItem(
+        reg_root, version_key, google_update::kRegRenameCmdField);
   }
   installer::InstallStatus ret = installer::RENAME_SUCCESSFUL;
   if (!install_list->Do()) {
     LOG(ERROR) << "Renaming of executables failed. Rolling back any changes.";
     install_list->Rollback();
     ret = installer::RENAME_FAILED;
   }
   // temp_path's dtor will take care of deleting or scheduling itself for
   // deletion at reboot when this scope closes.
   VLOG(1) << "Deleting temporary directory " << temp_path.path().value();
@@ skipping 1082 matching lines @@
   if (!(installer_state.is_msi() && is_uninstall))
     // Note that we allow the status installer::UNINSTALL_REQUIRES_REBOOT
     // to pass through, since this is only returned on uninstall which is
     // never invoked directly by Google Update.
     return_code = InstallUtil::GetInstallReturnCode(install_status);
 
   VLOG(1) << "Installation complete, returning: " << return_code;
 
   return return_code;
 }