Fixed proxy settings button behaviour: it becomes disabled when device isn't connected to any netwo…

ash/system/tray/system_tray_delegate.h

Index: ash/system/tray/system_tray_delegate.h
diff --git a/ash/system/tray/system_tray_delegate.h b/ash/system/tray/system_tray_delegate.h
index 528c6460a929ae4fad4f0ee34788ff9f6197f7ae..e4fa9f308656e3135c5f1c45385b2be8714c802d 100644
--- a/ash/system/tray/system_tray_delegate.h
+++ b/ash/system/tray/system_tray_delegate.h
@@ -253,6 +253,9 @@ class SystemTrayDelegate {
   // Shows UI to search for cellular networks.
   virtual void ShowOtherCellular() = 0;
 
+  // Returns whether the system is connected to any network.
+  virtual bool IsNetworkConnected() = 0;
+
   // Returns whether wifi is available.
   virtual bool GetWifiAvailable() = 0;