chromeos: Fix crash when clicking on networking menu under mash

ash/system/network/network_list.cc

 // Copyright 2016 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 "ash/system/network/network_list.h"
 
 #include <memory>
 
+#include "ash/public/cpp/config.h"
 #include "ash/shell.h"
 #include "ash/shell_port.h"
 #include "ash/strings/grit/ash_strings.h"
 #include "ash/system/network/network_icon.h"
 #include "ash/system/network/network_icon_animation.h"
 #include "ash/system/network/network_info.h"
 #include "ash/system/network/network_state_list_detailed_view.h"
 #include "ash/system/networking_config_delegate.h"
 #include "ash/system/tray/fixed_sized_image_view.h"
 #include "ash/system/tray/hover_highlight_view.h"
@@ skipping 499 matching lines @@
     container()->ScrollRectToVisible(selected_view->bounds());
 }
 
 std::unique_ptr<std::set<std::string>>
 NetworkListView::UpdateNetworkListEntries() {
   NetworkStateHandler* handler = NetworkHandler::Get()->network_state_handler();
 
   // Keep an index where the next child should be inserted.
   int index = 0;
 
-  bool show_connection_warning =
+  // Show a warning that the connection might be monitored if connected to a VPN
+  // or if the default network has a proxy installed.
+  const bool using_vpn =
       !!NetworkHandler::Get()->network_state_handler()->ConnectedNetworkByType(
           NetworkTypePattern::VPN());
-  show_connection_warning =
-      show_connection_warning || NetworkHandler::Get()
-                                     ->ui_proxy_config_service()
-                                     ->HasDefaultNetworkProxyConfigured();
-
-  if (show_connection_warning) {
+  // TODO(jamescook): Eliminate the null check by creating UIProxyConfigService
+  // under mash. This will require the mojo pref service to work with prefs in
+  // Local State. http://crbug.com/718072
+  const bool using_proxy = NetworkHandler::Get()->ui_proxy_config_service() &&
+                           NetworkHandler::Get()
+                               ->ui_proxy_config_service()
+                               ->HasDefaultNetworkProxyConfigured();
+  if (using_vpn || using_proxy) {
     if (!connection_warning_)
       connection_warning_ = CreateConnectionWarning();
     PlaceViewAtIndex(connection_warning_, index++);
   }
 
   // First add high-priority networks (not Wi-Fi nor cellular).
   std::unique_ptr<std::set<std::string>> new_guids =
       UpdateNetworkChildren(NetworkInfo::Type::UNKNOWN, index);
   index += new_guids->size();
 
@@ skipping 269 matching lines @@
   TrayPopupItemStyle style(TrayPopupItemStyle::FontStyle::DETAILED_VIEW_LABEL);
   style.SetupLabel(label);
   connection_warning->AddView(TriView::Container::CENTER, label);
 
   // Nothing to the right of the text.
   connection_warning->SetContainerVisible(TriView::Container::END, false);
   return connection_warning;
 }
 
 }  // namespace ash