AGC: Removing unnneccessary copying and changing to using const

The changes have been shown to be bitexact on a large dataset.

Bug: webrtc:10859
Change-Id: Iedc0e9e944ebfabb717dd7fb4d2682c695da883e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/159694
Reviewed-by: Benjamin Wright <benwright@webrtc.org>
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Commit-Queue: Benjamin Wright <benwright@webrtc.org>
Commit-Queue: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29883}
diff --git a/modules/audio_processing/gain_control_unittest.cc b/modules/audio_processing/gain_control_unittest.cc
index 8014f8a..81e6899 100644
--- a/modules/audio_processing/gain_control_unittest.cc
+++ b/modules/audio_processing/gain_control_unittest.cc
@@ -31,9 +31,9 @@
   }
 
   std::vector<int16_t> render_audio;
-  GainControlImpl::PackRenderAudioBuffer(render_audio_buffer, &render_audio);
+  GainControlImpl::PackRenderAudioBuffer(*render_audio_buffer, &render_audio);
   gain_controller->ProcessRenderAudio(render_audio);
-  gain_controller->AnalyzeCaptureAudio(capture_audio_buffer);
+  gain_controller->AnalyzeCaptureAudio(*capture_audio_buffer);
   gain_controller->ProcessCaptureAudio(capture_audio_buffer, false);
 
   if (sample_rate_hz > AudioProcessing::kSampleRate16kHz) {