* FSFile should not be responsible for handling this much logic.
* Make more MediaHandler classes aware of the fact that an object
other than File might be passed in. Use the FSFile instead of a
useless empty stdClass object.
* Also added more fields to FSFile::placeholderProps to make it
more complete.
Change-Id: I9fe764b2a7261af507c6555e6a57273cf7d00d36