MacViews: Allow the toolkit-views Enterprise Signin Confirmation Dialog to be used

chrome/browser/ui/cocoa/tab_dialogs_views_mac.mm

 // Copyright 2017 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/ui/cocoa/tab_dialogs_views_mac.h"
 
 #include "chrome/browser/ui/views/collected_cookies_views.h"
+#include "chrome/browser/ui/views/sync/profile_signin_confirmation_dialog_views.h"
 
 TabDialogsViewsMac::TabDialogsViewsMac(content::WebContents* contents)
     : TabDialogsCocoa(contents) {}
 
 TabDialogsViewsMac::~TabDialogsViewsMac() {}
 
 void TabDialogsViewsMac::ShowCollectedCookies() {
   // Deletes itself on close.
   new CollectedCookiesViews(web_contents());
 }
+
+void TabDialogsViewsMac::ShowProfileSigninConfirmation(
+    Browser* browser,
+    Profile* profile,
+    const std::string& username,
+    std::unique_ptr<ui::ProfileSigninConfirmationDelegate> delegate) {
+  ProfileSigninConfirmationDialogViews::ShowDialog(browser, profile, username,
+                                                   std::move(delegate));
+}