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/util/phased_loop.h b/aos/util/phased_loop.h
index 64a3302..dc2dc96 100644
--- a/aos/util/phased_loop.h
+++ b/aos/util/phased_loop.h
@@ -5,8 +5,7 @@
 
 #include "aos/time/time.h"
 
-namespace aos {
-namespace time {
+namespace aos::time {
 
 // Handles sleeping until a fixed offset from some time interval.
 class PhasedLoop {
@@ -88,7 +87,6 @@
   monotonic_clock::time_point last_time_ = monotonic_clock::epoch();
 };
 
-}  // namespace time
-}  // namespace aos
+}  // namespace aos::time
 
 #endif  // AOS_UTIL_PHASED_LOOP_H_