Allow extracting the linear AEC output

This CL enables extracting the linear AEC output,
allowing for more straightforward
testing/development.

Bug: b/140823178
Change-Id: I14f7934008d87066b35500466cb6e6d96f811688
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/153672
Commit-Queue: Per Åhgren <peah@webrtc.org>
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29789}
diff --git a/modules/audio_processing/test/echo_control_mock.h b/modules/audio_processing/test/echo_control_mock.h
index c2082c2..95d3be5 100644
--- a/modules/audio_processing/test/echo_control_mock.h
+++ b/modules/audio_processing/test/echo_control_mock.h
@@ -24,6 +24,10 @@
   MOCK_METHOD1(AnalyzeCapture, void(AudioBuffer* capture));
   MOCK_METHOD2(ProcessCapture,
                void(AudioBuffer* capture, bool echo_path_change));
+  MOCK_METHOD3(ProcessCapture,
+               void(AudioBuffer* capture,
+                    AudioBuffer* linear_output,
+                    bool echo_path_change));
   MOCK_CONST_METHOD0(GetMetrics, EchoControl::Metrics());
   MOCK_METHOD1(SetAudioBufferDelay, void(int delay_ms));
   MOCK_CONST_METHOD0(ActiveProcessing, bool());