AEC3: ERLE: Allowing increases of the ERLE estimate for low render signals.

Specially for devices with high echo path gain, even low render signal can allow the linear filter of the AEC3 to converge. However, the conditions that were used for updating the ERLE avoided to update that estimation. In this commit, we allow adapting the ERLE estimator using even low render signal but the update of the ERLE is constraint in a way that decreases are not allowed.

Bug: webrtc:9776
Change-Id: Ic4331efcc47a0b05f394cdea9a88f336292de5a1
Reviewed-on: https://webrtc-review.googlesource.com/101641
Commit-Queue: Jesus de Vicente Pena <devicentepena@webrtc.org>
Reviewed-by: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24859}

modules/audio_processing/aec3/aec_state.h

@@ -82,10 +82,8 @@ class AecState {
     return absl::nullopt;
   }
 
-  // Returns the time-domain ERLE in log2 units.
-  float ErleTimeDomainLog2() const {
-    return erle_estimator_.ErleTimeDomainLog2();
-  }
+  // Returns the fullband ERLE estimate in log2 units.
+  float FullBandErleLog2() const { return erle_estimator_.FullbandErleLog2(); }
 
   // Returns the ERL.
   const std::array<float, kFftLengthBy2Plus1>& Erl() const {