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/y2019/vision/constants.h b/y2019/vision/constants.h
index 959f5b7..7078d6b 100644
--- a/y2019/vision/constants.h
+++ b/y2019/vision/constants.h
@@ -6,8 +6,7 @@
 #include <cstdint>
 #include <string>
 
-namespace y2019 {
-namespace vision {
+namespace y2019::vision {
 
 // Position of the idealized camera in 3d space.
 struct CameraGeometry {
@@ -107,7 +106,6 @@
 void DumpCameraConstants(const char *fname, int camera_id,
                          const CameraCalibration &value);
 
-}  // namespace vision
-}  // namespace y2019
+}  // namespace y2019::vision
 
 #endif  // _Y2019_VISION_CONSTANTS_H_
diff --git a/y2019/vision/image_writer.h b/y2019/vision/image_writer.h
index 1192368..27dcb4a 100644
--- a/y2019/vision/image_writer.h
+++ b/y2019/vision/image_writer.h
@@ -5,8 +5,7 @@
 
 #include "aos/vision/image/image_types.h"
 
-namespace y2019 {
-namespace vision {
+namespace y2019::vision {
 
 class ImageWriter {
  public:
@@ -23,7 +22,6 @@
   unsigned int image_count_ = 0;
 };
 
-}  // namespace vision
-}  // namespace y2019
+}  // namespace y2019::vision
 
 #endif  // Y2019_VISION_IMAGE_WRITER_H_
diff --git a/y2019/vision/target_finder.h b/y2019/vision/target_finder.h
index fdcfbde..20bf87a 100644
--- a/y2019/vision/target_finder.h
+++ b/y2019/vision/target_finder.h
@@ -16,8 +16,7 @@
 class Context;
 
 }  // namespace ceres
-namespace y2019 {
-namespace vision {
+namespace y2019::vision {
 
 using aos::vision::BlobList;
 using aos::vision::ContourNode;
@@ -115,7 +114,6 @@
   int current_exposure_ = 0;
 };
 
-}  // namespace vision
-}  // namespace y2019
+}  // namespace y2019::vision
 
 #endif
diff --git a/y2019/vision/target_types.h b/y2019/vision/target_types.h
index 5019646..fb57b71 100644
--- a/y2019/vision/target_types.h
+++ b/y2019/vision/target_types.h
@@ -7,8 +7,7 @@
 #include "aos/vision/math/vector.h"
 #include "y2019/vision/constants.h"
 
-namespace y2019 {
-namespace vision {
+namespace y2019::vision {
 
 // This polynomial exists in transpose space.
 struct TargetComponent {
@@ -239,7 +238,6 @@
                                   240.0 - res.y() * scale);
 }
 
-}  // namespace vision
-}  // namespace y2019
+}  // namespace y2019::vision
 
 #endif