Nest some more namespaces

Did someone previously suggest that all namespace had been
nested?  Silly.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I22278c1caaeba8b47dc46fb2ed3078c20a11e190
diff --git a/aos/vision/blob/range_image.h b/aos/vision/blob/range_image.h
index d962788..10e801f 100644
--- a/aos/vision/blob/range_image.h
+++ b/aos/vision/blob/range_image.h
@@ -5,8 +5,7 @@
 
 #include "aos/vision/image/image_types.h"
 
-namespace aos {
-namespace vision {
+namespace aos::vision {
 
 struct Point {
   int x;
@@ -100,7 +99,6 @@
 // Debug print range image as ### for the ranges.
 void DebugPrint(const BlobList &blobl);
 
-}  // namespace vision
-}  // namespace aos
+}  // namespace aos::vision
 
 #endif  // _AOS_VISION_BLOB_RANGE_IMAGE_H_