Crash fix for system tray. We try to enable proxy settings entry even while there are created.

ash/system/network/tray_network.cc

Index: ash/system/network/tray_network.cc
diff --git a/ash/system/network/tray_network.cc b/ash/system/network/tray_network.cc
index 1a02308b129ddad630a305a30b52f9e7a8929bb5..95e588ea584402e113d41cd5a3003f7c0b09cf22 100644
--- a/ash/system/network/tray_network.cc
+++ b/ash/system/network/tray_network.cc
@@ -242,7 +242,8 @@ class NetworkDetailedView : public TrayDetailsView,
     button_wifi_->SetToggled(!delegate->GetWifiEnabled());
     button_mobile_->SetToggled(!delegate->GetMobileEnabled());
     button_mobile_->SetVisible(delegate->GetMobileAvailable());
-    proxy_settings_->SetEnabled(delegate->IsNetworkConnected());
+    if (proxy_settings_)
+      proxy_settings_->SetEnabled(delegate->IsNetworkConnected());
   }
 
   void AppendNetworkEntries() {
@@ -335,6 +336,7 @@ class NetworkDetailedView : public TrayDetailsView,
     bottom_row->AddTextButton(other_mobile_);
 
     CreateSettingsEntry();
+    DCHECK(settings_ || proxy_settings_);
     bottom_row->AddTextButton(settings_ ? settings_ : proxy_settings_);
 
     AddChildView(bottom_row);