Add missing dependency to audio_decoder_unittests.

BUG=None
NOTRY=True
R=kjellander@webrtc.org

Review-Url: https://codereview.webrtc.org/2684573002
Cr-Original-Commit-Position: refs/heads/master@{#16470}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 87b8e9f3a24dfc08f3e3f9bf5cf8f01c2ae04a4c
1 file changed