Make ExtensionInstallPrompt::Prompt ref-counted

chrome/browser/ui/android/extensions/extension_install_dialog_android.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 "base/bind.h"
 #include "chrome/browser/extensions/extension_install_prompt.h"
 
 namespace {
 
 void ShowExtensionInstallDialogImpl(
     const ExtensionInstallPrompt::ShowParams& show_params,
     ExtensionInstallPrompt::Delegate* delegate,
-    const ExtensionInstallPrompt::Prompt& prompt) {
+    scoped_refptr<ExtensionInstallPrompt::Prompt> prompt) {
   NOTIMPLEMENTED();
 }
 
 }  // namespace
 
 // static
 ExtensionInstallPrompt::ShowDialogCallback
 ExtensionInstallPrompt::GetDefaultShowDialogCallback() {
   return base::Bind(&ShowExtensionInstallDialogImpl);
 }