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/y2017/vision/target_finder.h b/y2017/vision/target_finder.h
index 34fd90d..5c89a6d 100644
--- a/y2017/vision/target_finder.h
+++ b/y2017/vision/target_finder.h
@@ -11,8 +11,7 @@
 using aos::vision::RangeImage;
 using aos::vision::Vector;
 
-namespace y2017 {
-namespace vision {
+namespace y2017::vision {
 
 // This polynomial exists in transpose space.
 struct TargetComponent {
@@ -84,7 +83,6 @@
   aos::vision::PixelLinesOverlay overlay_;
 };
 
-}  // namespace vision
-}  // namespace y2017
+}  // namespace y2017::vision
 
 #endif  // _Y2017_VISION_TARGET_FINDER_H_