Add missing files to audio_processing.

Bug: webrtc:7621
Change-Id: I2cab764232fc4e084ed8a489f4cf3a3ac562c894
Reviewed-on: https://webrtc-review.googlesource.com/34658
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21461}
diff --git a/audio/BUILD.gn b/audio/BUILD.gn
index 8459385..afebe93 100644
--- a/audio/BUILD.gn
+++ b/audio/BUILD.gn
@@ -108,6 +108,7 @@
       "../modules/audio_device:mock_audio_device",
       "../modules/audio_mixer:audio_mixer_impl",
       "../modules/audio_processing:audio_processing_statistics",
+      "../modules/audio_processing:mocks",
       "../modules/congestion_controller:congestion_controller",
       "../modules/congestion_controller:mock_congestion_controller",
       "../modules/pacing:mock_paced_sender",