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/events/timing_statistics.cc b/aos/events/timing_statistics.cc
index caf71da..ea3f2d2 100644
--- a/aos/events/timing_statistics.cc
+++ b/aos/events/timing_statistics.cc
@@ -4,8 +4,7 @@
 
 #include "aos/events/event_loop_generated.h"
 
-namespace aos {
-namespace internal {
+namespace aos::internal {
 
 void RawFetcherTiming::set_timing_report(timing::Fetcher *new_fetcher) {
   fetcher = new_fetcher;
@@ -74,5 +73,4 @@
   timer->mutate_count(0);
 }
 
-}  // namespace internal
-}  // namespace aos
+}  // namespace aos::internal