Support an --install-from-webstore command line switch

chrome/browser/extensions/extension_install_dialog.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_install_dialog.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 50 matching lines @@
 
 void ShowExtensionInstallDialog(gfx::NativeWindow parent,
                                 content::PageNavigator* navigator,
                                 ExtensionInstallPrompt::Delegate* delegate,
                                 const ExtensionInstallPrompt::Prompt& prompt) {
   AutoConfirmForTest auto_confirm = CheckAutoConfirmCommandLineSwitch();
   if (auto_confirm != DO_NOT_SKIP) {
     DoAutoConfirm(auto_confirm, delegate);
     return;
   }
-  if (!parent) {
-    delegate->InstallUIAbort(false);
-    return;
-  }
   ShowExtensionInstallDialogImpl(parent, navigator, delegate, prompt);
 }