Nest all namespaces

The compiler supports this now.  We can type less going forward.
No functional changes.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I29d6fa4f9aacc0e381f1a7637294db0392466995
diff --git a/y2017/vision/debug_viewer.cc b/y2017/vision/debug_viewer.cc
index 79b9800..073f8e5 100644
--- a/y2017/vision/debug_viewer.cc
+++ b/y2017/vision/debug_viewer.cc
@@ -14,8 +14,7 @@
 using aos::vision::ImageRange;
 using aos::vision::RangeImage;
 
-namespace y2017 {
-namespace vision {
+namespace y2017::vision {
 
 BlobList RenderTargetListShifted(const std::vector<TargetComponent> &list) {
   BlobList out;
@@ -120,8 +119,7 @@
   std::vector<aos::vision::OverlayBase *> overlays_;
 };
 
-}  // namespace vision
-}  // namespace y2017
+}  // namespace y2017::vision
 
 int main(int argc, char **argv) {
   y2017::vision::FilterHarnessExample filter_harness;
diff --git a/y2017/vision/target_finder.cc b/y2017/vision/target_finder.cc
index e917b2e..640c7fe 100644
--- a/y2017/vision/target_finder.cc
+++ b/y2017/vision/target_finder.cc
@@ -2,8 +2,7 @@
 
 #include <cmath>
 
-namespace y2017 {
-namespace vision {
+namespace y2017::vision {
 
 // Blobs now come in three types:
 //  0) normal blob.
@@ -276,5 +275,4 @@
   *angle = -std::atan2(px, pz);
 }
 
-}  // namespace vision
-}  // namespace y2017
+}  // namespace y2017::vision
diff --git a/y2017/vision/target_receiver.cc b/y2017/vision/target_receiver.cc
index f21fe4e..fd9f7d8 100644
--- a/y2017/vision/target_receiver.cc
+++ b/y2017/vision/target_receiver.cc
@@ -9,8 +9,7 @@
 #include "y2017/vision/vision_generated.h"
 #include "y2017/vision/vision_result.pb.h"
 
-namespace y2017 {
-namespace vision {
+namespace y2017::vision {
 
 using aos::monotonic_clock;
 
@@ -70,8 +69,7 @@
   }
 }
 
-}  // namespace vision
-}  // namespace y2017
+}  // namespace y2017::vision
 
 int main(int argc, char **argv) {
   ::aos::InitGoogle(&argc, &argv);
diff --git a/y2017/vision/target_sender.cc b/y2017/vision/target_sender.cc
index a198cd2..1e6e049 100644
--- a/y2017/vision/target_sender.cc
+++ b/y2017/vision/target_sender.cc
@@ -27,8 +27,7 @@
 #include "y2017/vision/vision_config.pb.h"
 #include "y2017/vision/vision_result.pb.h"
 
-namespace y2017 {
-namespace vision {
+namespace y2017::vision {
 
 using aos::events::DataSocket;
 using aos::events::TCPServer;
@@ -215,8 +214,7 @@
   return true;
 }
 
-}  // namespace vision
-}  // namespace y2017
+}  // namespace y2017::vision
 
 int main(int, char **) {
   using namespace y2017::vision;