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/aos/vision/debug/debug_framework.cc b/aos/vision/debug/debug_framework.cc
index 0b0d2c7..770eefd 100644
--- a/aos/vision/debug/debug_framework.cc
+++ b/aos/vision/debug/debug_framework.cc
@@ -9,8 +9,7 @@
 #include "aos/vision/events/epoll_events.h"
 #include "aos/vision/image/jpeg_routines.h"
 
-namespace aos {
-namespace vision {
+namespace aos::vision {
 
 // Detect screen height on smaller monitors.
 int GetScreenHeight() {
@@ -176,5 +175,4 @@
   replay.Loop()->RunWithGtkMain();
 }
 
-}  // namespace vision
-}  // namespace aos
+}  // namespace aos::vision