Moving It2Me confirmation prompt into the Validation callback flow

remoting/host/it2me/it2me_confirmation_dialog.h

Index: remoting/host/it2me/it2me_confirmation_dialog.h
diff --git a/remoting/host/it2me/it2me_confirmation_dialog.h b/remoting/host/it2me/it2me_confirmation_dialog.h
index 2e51ae7fc074c7b3fc2ab667ad75d3a3953c475e..57e266933445bee5c6c8a566023f191551a4bdfa 100644
--- a/remoting/host/it2me/it2me_confirmation_dialog.h
+++ b/remoting/host/it2me/it2me_confirmation_dialog.h
@@ -30,7 +30,8 @@ class It2MeConfirmationDialog {
 
   // Shows the dialog. |callback| will be called with the user's selection.
   // |callback| will not be called if the dialog is destroyed.
-  virtual void Show(const ResultCallback& callback) = 0;
+  virtual void Show(const std::string& remote_user_email,
+                    const ResultCallback& callback) = 0;
 };
 
 // Used to create an platform specific instance of It2MeConfirmationDialog.