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/network/testing_time_converter.h b/aos/network/testing_time_converter.h
index ae85cee..768d0a2 100644
--- a/aos/network/testing_time_converter.h
+++ b/aos/network/testing_time_converter.h
@@ -10,8 +10,7 @@
 #include "aos/network/multinode_timestamp_filter.h"
 #include "aos/time/time.h"
 
-namespace aos {
-namespace message_bridge {
+namespace aos::message_bridge {
 
 // Simple class to which uses InterpolatedTimeConverter to produce an
 // interpolated timeline.  Should only be used for testing.
@@ -77,7 +76,6 @@
   std::map<std::pair<size_t, size_t>, UUID> boot_uuids_;
 };
 
-}  // namespace message_bridge
-}  // namespace aos
+}  // namespace aos::message_bridge
 
 #endif  // AOS_NETWORK_TESTING_TIME_CONVERTER_H_