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/simulated_network_bridge.cc b/aos/events/simulated_network_bridge.cc
index 3ed39fa..5c97292 100644
--- a/aos/events/simulated_network_bridge.cc
+++ b/aos/events/simulated_network_bridge.cc
@@ -7,8 +7,7 @@
 #include "aos/events/simulated_event_loop.h"
 #include "aos/network/remote_message_generated.h"
 
-namespace aos {
-namespace message_bridge {
+namespace aos::message_bridge {
 
 // This class delays messages forwarded between two factories.
 //
@@ -760,5 +759,4 @@
   });
 }
 
-}  // namespace message_bridge
-}  // namespace aos
+}  // namespace aos::message_bridge