Make show_dialog_callback optional in ExtensionInstallPrompt

chrome/browser/extensions/webstore_installer.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/webstore_installer.h"
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/file_util.h"
@@ skipping 133 matching lines @@
     const std::string& id,
     content::DownloadItem* item) {
 }
 
 WebstoreInstaller::Approval::Approval()
     : profile(NULL),
       use_app_installed_bubble(false),
       skip_post_install_ui(false),
       skip_install_dialog(false),
       record_oauth2_grant(false) {
-  show_dialog_callback = ExtensionInstallPrompt::GetDefaultShowDialogCallback();
 }
 
 scoped_ptr<WebstoreInstaller::Approval>
 WebstoreInstaller::Approval::CreateWithInstallPrompt(Profile* profile) {
   scoped_ptr<Approval> result(new Approval());
   result->profile = profile;
   return result.Pass();
 }
 
 scoped_ptr<WebstoreInstaller::Approval>
@@ skipping 213 matching lines @@
 void WebstoreInstaller::ReportSuccess() {
   if (delegate_) {
     delegate_->OnExtensionInstallSuccess(id_);
     delegate_ = NULL;
   }
 
   Release();  // Balanced in Start().
 }
 
 }  // namespace extensions