Make the nonlinear beamformer steerable

Depends on this CL: https://codereview.webrtc.org/1395453004/

R=andrew@webrtc.org

Review URL: https://codereview.webrtc.org/1394103003 .

Cr-Commit-Position: refs/heads/master@{#10458}
diff --git a/webrtc/modules/modules.gyp b/webrtc/modules/modules.gyp
index 2bf0ac8..f3ac454 100644
--- a/webrtc/modules/modules.gyp
+++ b/webrtc/modules/modules.gyp
@@ -171,6 +171,7 @@
             'audio_processing/beamformer/covariance_matrix_generator_unittest.cc',
             'audio_processing/beamformer/matrix_unittest.cc',
             'audio_processing/beamformer/mock_nonlinear_beamformer.h',
+            'audio_processing/beamformer/nonlinear_beamformer_unittest.cc',
             'audio_processing/echo_cancellation_impl_unittest.cc',
             'audio_processing/intelligibility/intelligibility_enhancer_unittest.cc',
             'audio_processing/intelligibility/intelligibility_utils_unittest.cc',