chromeos: Refactor system tray ShowNetworkSettingsForGuid for mash

ash/common/system/tray/system_tray_delegate.h

Index: ash/common/system/tray/system_tray_delegate.h
diff --git a/ash/common/system/tray/system_tray_delegate.h b/ash/common/system/tray/system_tray_delegate.h
index ef402521d01cac32143ddfb30ad7562ecc35e1aa..1c9da5a67c862563281067325fe5b2ebed1c6c06 100644
--- a/ash/common/system/tray/system_tray_delegate.h
+++ b/ash/common/system/tray/system_tray_delegate.h
@@ -147,10 +147,6 @@ class ASH_EXPORT SystemTrayDelegate {
   // Shows the dialog to set system time, date, and timezone.
   virtual void ShowSetTimeDialog();
 
-  // Shows the settings related to network. If |guid| is not empty,
-  // show the settings for the corresponding network.
-  virtual void ShowNetworkSettingsForGuid(const std::string& guid);
-
   // Returns true if the notification for the display configuration change
   // should appear.
   virtual bool ShouldShowDisplayNotification();