In the test, a real instance of SimpleExoplayer plays two identical Mp3 files.
The GaplessMp3Decoder will write randomized data to decoder output on receiving
input. The test compares the bytes written by the decoder with the bytes
received by the AudioTrack, to verify that the trimming of encoder delay/
padding is correctly carried out.

Test mp3 has delay 576 frames and padding 1404 frames. File generated from:
ffmpeg -f lavfi -i "sine=frequency=1000:duration=1" test.mp3

This change needs robolectric version 4.5, which is not currently released (2020 Sep 30).

PiperOrigin-RevId: 334648486