message: Extract register_activity.
diff: @@ -994,8 +994,7 @@ impl<C: Context + 'static> SimpleConsensus<C> {
  .round_mut(round_id)
  .insert_proposal(proposal, signature)
  {
  - self.progress_detected = true;
  - self.active[validator_idx] = true;
  + self.register_activity(validator_idx);
  return true;
  }
  }
  @@ -1005,8 +1004,7 @@ impl<C: Context + 'static> SimpleConsensus<C> {
  .round_mut(round_id)
  .insert_echo(hash, validator_idx, signature)
  {
  - self.progress_detected = true;
  - self.active[validator_idx] = true;
  + self.register_activity(validator_idx);
  return self.check_new_echo_quorum(round_id, hash);
  }
  }
  @@ -1016,8 +1014,7 @@ impl<C: Context + 'static> SimpleConsensus<C> {
  .round_mut(round_id)
  .insert_vote(vote, validator_idx, signature)
  {
  - self.progress_detected = true;
  - self.active[validator_idx] = true;
  + self.register_activity(validator_idx);
  return self.check_new_vote_quorum(round_id, vote);
  }
  }
  @@ -1025,6 +1022,12 @@ impl<C: Context + 'static> SimpleConsensus<C> {
  false
  }
  + /// Update the state after a new siganture from a validator was received.
  + fn register_activity(&mut self, validator_idx: ValidatorIndex) {
  + self.progress_detected = true;
  + self.active[validator_idx] = true;
  + }
  +
  /// If there is a signature for conflicting content, returns the content and signature.
  fn detect_fault(
  &self,
  