message: Clear segments before Suggest.
  Suggest can be called twice in series around the STOP_KEY_TOGGLING command.
diff: @@ -436,6 +436,8 @@ bool SessionConverter::SuggestWithPreferences(
  // Initialize the conversion request and segments for suggestion.
  SetConversionPreferences(preferences, segments_.get(), &conversion_request);
  + segments_->clear_conversion_segments();
  +
  const size_t cursor = composer.GetCursor();
  if (cursor == composer.GetLength() || cursor == 0 ||
  !request_->mixed_conversion()) {
  