Guesses the content type based on example data.
If the function is uncertain, result_uncertain will be set to true. Either filename
or data may be null, in which case the guess will be based solely on the other
argument.
| filename |
a path, or null |
| data |
a stream of data, or null |
| result_uncertain |
return location for the certainty of the result, or null |
| data_size |
the size of |
|
a string indicating a guessed content type for the given data. Free with g_free |