[cros] Add network tray item for mobile network setup.

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 c3992964e4554752c066fb1805b6797042fd8df1..10db34d21528be322d8810e65ebbc1271fb58072 100644
--- a/ash/system/tray/system_tray_delegate.h
+++ b/ash/system/tray/system_tray_delegate.h
@@ -229,10 +229,11 @@ class SystemTrayDelegate {
   // Retrieves information about the carrier. If the information cannot be
   // retrieved, returns false.
   virtual bool GetCellularCarrierInfo(std::string* carrier_id,
-                                      std::string* toup_url) = 0;
+                                      std::string* topup_url,
+                                      std::string* setup_url) = 0;
 
-  // Opens the top up url.
-  virtual void ShowCellularTopupURL(const std::string& topup_url) = 0;
+  // Opens the cellular network specific URL.
+  virtual void ShowCellularURL(const std::string& url) = 0;
 
   // Shows UI for changing proxy settings.
   virtual void ChangeProxySettings() = 0;