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/events/timing_statistics.h b/aos/events/timing_statistics.h
index 3c8c741..ef07254 100644
--- a/aos/events/timing_statistics.h
+++ b/aos/events/timing_statistics.h
@@ -6,8 +6,7 @@
 #include "aos/events/event_loop_generated.h"
 #include "aos/util/error_counter.h"
 
-namespace aos {
-namespace internal {
+namespace aos::internal {
 
 // Class to compute statistics for the timing report.
 class TimingStatistic {
@@ -113,7 +112,6 @@
   timing::Timer *timer = nullptr;
 };
 
-}  // namespace internal
-}  // namespace aos
+}  // namespace aos::internal
 
 #endif  // AOS_EVENTS_TIMING_STATISTICS_H_