[traffic] Throttle UI/router refresh while messages are being processed

Signed-off-by: mvglasow <michael -at- vonglasow.com>

map/traffic_manager.hpp

@@ -488,6 +488,16 @@ private:
    */
   std::chrono::time_point<std::chrono::steady_clock> m_lastResponseTime;
 
+  /**
+   * @brief When the last update notification to the Drape engine was posted.
+   */
+  std::chrono::time_point<std::chrono::steady_clock> m_lastDrapeUpdate;
+
+  /**
+   * @brief When the last update notification to the traffic observer was posted.
+   */
+  std::chrono::time_point<std::chrono::steady_clock> m_lastObserverUpdate;
+
   /**
    * @brief Whether active MWMs have changed since the last request.
    */