Getting the Page control from "this"

 I have a function call on a page called "AddUser.aspx". I'm passing "this" to the function, and in the function itself I want to know from which page it has arrived, because I want to get to the master-master page. Therefore I need to gain access to the "Page" object from "this", but I don't find a proper way to do so.
I also tried to pass "Page" and to recognise it as a typeof(Page) :
 
1 if (owner.GetType() == typeof(Page))
  But it didn't work also.
Is there a way to do it ?
 
 
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