adds the API getMetrics() to android.media.MediaExtractor includes plumbing through JNI to the underlying mediaextractor code in frameworks/av. Tested with some CTS modifications; a more formal set of CTS updates will be along later. Bug: 35094936 Test: modified CTS to invoke new API and output results Change-Id: Id8d56c9c3273b86bbd11e248bdf5004be90b91ef