[libuvc_camera/src/camera_driver.cpp] use frame's capture time for timestamp...

[libuvc_camera/src/camera_driver.cpp] use frame's capture time for timestamp of ros message instead of callback time

libuvc_camera/src/camera_driver.cpp

@@ -157,8 +157,7 @@ void CameraDriver::ReconfigureCallback(UVCCameraConfig &new_config, uint32_t lev
 }
 
 void CameraDriver::ImageCallback(uvc_frame_t *frame) {
-  // TODO: Switch to {frame}'s timestamp once that becomes reliable.
-  ros::Time timestamp = ros::Time::now();
+  ros::Time timestamp = ros::Time(frame->capture_time.tv_sec, frame->capture_time.tv_usec);
 
   boost::recursive_mutex::scoped_lock(mutex_);