Initialize more of the visualization_manager members. (ros-visualizat…

…ion#1090) (ros-visualization#1091)

This is so we don't access uninitialized memory during
startup.

Signed-off-by: Chris Lalancette <clalancette@gmail.com>
(cherry picked from commit 51e576c5289a5d231f89c7593ded84c6ddade22f)

Co-authored-by: Chris Lalancette <clalancette@gmail.com>

rviz_common/src/rviz_common/visualization_manager.cpp

@@ -146,6 +146,8 @@ VisualizationManager::VisualizationManager(
   update_timer_(0),
   shutting_down_(false),
   render_panel_(render_panel),
+  wall_clock_elapsed_(0),
+  ros_time_elapsed_(0),
   time_update_timer_(0.0f),
   frame_update_timer_(0.0f),
   render_requested_(1),