Ron - No! I have not heard the mayor of Los Angeles endorse the idea of giving parts of the US back to Mexico. But I don't think you've interpreted the concept of Aztlan as the followers intended. The mayor is, however, trying to make the city a haven for illegals under the pretext that it would be bad for the economy not to.
                   The question that remains to be asked then is this: who's economy is he worried about?