verbs - Meaning of "mulling a factory"?

A Japanese newspaper partly held by Toyota reported a month later that
the carmaker was mulling a factory in Brazil for production of the
same car.

[Source]

I couldn't find a phrase 'mulling a factory' in any dictionary, hence I instead searched 'mull' in Merriam-Webster.

1. to grind or mix thoroughly




2. to consider at length : ponder —often used with over

I guess the meaning of 'mulling a factory' is 'founding or making a new factory', which has nothing to do with the meaning of 'mull'.

Is my guess correct? If it is, is 'mulling a factory' a common or natural expression?

Can you help me understand the phrase 'mulling a factory'?