Make the chrome://signin-error accessiable by the incogtino System Profile.

chrome/browser/ui/webui/chrome_web_ui_controller_factory.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/ui/webui/chrome_web_ui_controller_factory.h"
 
 #include <stddef.h>
 
 #include <vector>
 
@@ skipping 528 matching lines @@
   // extensions aren't supported.
   if (url.host_piece() == chrome::kChromeUIInspectHost)
     return &NewWebUI<InspectUI>;
 #endif
 #if !defined(OS_CHROMEOS) && !defined(OS_ANDROID)
   if (url.host_piece() == chrome::kChromeUIChromeSigninHost)
     return &NewWebUI<InlineLoginUI>;
   if (url.host_piece() == chrome::kChromeUIMdUserManagerHost)
     return &NewWebUI<MDUserManagerUI>;
   if (url.host_piece() == chrome::kChromeUISigninErrorHost &&
-      !profile->IsOffTheRecord())
+      (!profile->IsOffTheRecord() ||
+       profile->GetOriginalProfile()->IsSystemProfile()))
     return &NewWebUI<SigninErrorUI>;
   if (url.host_piece() == chrome::kChromeUISyncConfirmationHost &&
       !profile->IsOffTheRecord())
     return &NewWebUI<SyncConfirmationUI>;
   if (url.host_piece() == chrome::kChromeUISigninEmailConfirmationHost &&
       !profile->IsOffTheRecord())
     return &NewWebUI<SigninEmailConfirmationUI>;
   if (url.host_piece() == chrome::kChromeUIWelcomeHost)
     return &NewWebUI<WelcomeUI>;
 #endif
@@ skipping 263 matching lines @@
 
 #if BUILDFLAG(ENABLE_EXTENSIONS)
   if (page_url.host_piece() == chrome::kChromeUIExtensionsHost ||
       page_url.host_piece() == chrome::kChromeUIExtensionsFrameHost)
     return extensions::ExtensionsUI::GetFaviconResourceBytes(scale_factor);
 #endif  // BUILDFLAG(ENABLE_EXTENSIONS)
 #endif  // !defined(OS_ANDROID)
 
   return NULL;
 }