By far, the best pdf reader for android is EBookDroid PDF & DJVU Reader:
https://play.google.com/store/apps/d...roid&hl=es_419
Not only do what you want (zoom to content) but also can read pdf with columns (zoom to column so you can read one column at time). Besides you can highlight text, do free-hand annotations, notes, etc., etc. You won't need another app to read pdf and djvu files.
Regards
Rubén