Allow the headset mode to be entered after the call has started

This CL adds a timeout for the detection of the headset mode that
allows it to be entered also for the cases where a headset is
inserted during the call.

Bug: chromium:826720,webrtc:9083
Change-Id: Ic3cb4cc0258997a74eccd1bcdf65765e44016ad8
Reviewed-on: https://webrtc-review.googlesource.com/65240
Reviewed-by: Alessio Bazzica <alessiob@webrtc.org>
Commit-Queue: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22658}

modules/audio_processing/aec3/aec_state.cc

@@ -167,6 +167,12 @@ void AecState::Update(
     blocks_since_converged_filter_ =
         converged_filter ? 0 : blocks_since_converged_filter_ + 1;
   }
+  if (converged_filter) {
+    active_blocks_since_converged_filter_ = 0;
+  } else if (active_render_block) {
+    ++active_blocks_since_converged_filter_;
+  }
+
   bool recently_converged_filter =
       blocks_since_converged_filter_ < 60 * kNumBlocksPerSecond;
 
@@ -198,6 +204,13 @@ void AecState::Update(
 
   converged_filter_seen_ = converged_filter_seen_ || converged_filter;
 
+  // If no filter convergence is seen for a long time, reset the estimated
+  // properties of the echo path.
+  if (active_blocks_since_converged_filter_ > 60 * kNumBlocksPerSecond) {
+    converged_filter_seen_ = false;
+    finite_erl_ = false;
+  }
+
   // After an amount of active render samples for which an echo should have been
   // detected in the capture signal if the ERL was not infinite, flag that a
   // transparent mode should be entered.

modules/audio_processing/aec3/aec_state.h

@@ -175,6 +175,7 @@ class AecState {
   bool external_delay_seen_ = false;
   size_t converged_filter_count_ = 0;
   bool finite_erl_ = false;
+  size_t active_blocks_since_converged_filter_ = 0;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(AecState);
 };