Correcting the usage of the estimated echo path gain in AEC3

This CL corrects the usage of the estimated echo path gain to not be
hardcoded to 1. In order to retain the tuned behavior, the CL for now
maintains the former behavior in the code.

Bug: webrtc:9255,chromium:851187
Change-Id: I7f91c72e476680a8a854c22b74b1771fae446110
Reviewed-on: https://webrtc-review.googlesource.com/75510
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Commit-Queue: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23190}

modules/audio_processing/aec3/aec_state.h

@@ -49,7 +49,7 @@ class AecState {
   bool UseLinearFilterOutput() const { return use_linear_filter_output_; }
 
   // Returns the estimated echo path gain.
-  bool EchoPathGain() const { return filter_analyzer_.Gain(); }
+  float EchoPathGain() const { return filter_analyzer_.Gain(); }
 
   // Returns whether the render signal is currently active.
   bool ActiveRender() const { return blocks_with_active_render_ > 200; }