Don't register or use the DelegateExecute verb handler if it isn't present.

chrome/installer/setup/install_worker.h

 // 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.
 //
 // This file contains the declarations of the installer functions that build
 // the WorkItemList used to install the application.
 
 #ifndef CHROME_INSTALLER_SETUP_INSTALL_WORKER_H_
 #define CHROME_INSTALLER_SETUP_INSTALL_WORKER_H_
 #pragma once
@@ skipping 106 matching lines @@
 // installation.  This includes handling of the ready-mode option.
 void AddChromeFrameWorkItems(const InstallationState& original_state,
                              const InstallerState& installer_state,
                              const FilePath& setup_path,
                              const Version& new_version,
                              const Product& product,
                              WorkItemList* list);
 
 // Called for either installation or uninstallation. This method adds or
 // removes COM registration for a product's DelegateExecute verb handler.
-void AddDelegateExecuteWorkItems(const InstallationState& original_state,
-                                 const InstallerState& installer_state,
-                                 const FilePath& setup_path,
+void AddDelegateExecuteWorkItems(const InstallerState& installer_state,
+                                 const FilePath& src_path,
                                  const Version& new_version,
                                  const Product& product,
                                  WorkItemList* list);
 
 // This method adds work items to create (or update) Chrome uninstall entry in
 // either the Control Panel->Add/Remove Programs list or in the Omaha client
 // state key if running under an MSI installer.
 void AddUninstallShortcutWorkItems(const InstallerState& installer_state,
                                    const FilePath& setup_path,
                                    const Version& new_version,
@@ skipping 36 matching lines @@
 // (and may therefore be NULL) when uninstalling.
 void AddQuickEnableWorkItems(const InstallerState& installer_state,
                              const InstallationState& machine_state,
                              const FilePath* setup_path,
                              const Version* new_version,
                              WorkItemList* work_item_list);
 
 }  // namespace installer
 
 #endif  // CHROME_INSTALLER_SETUP_INSTALL_WORKER_H_