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/network/message_bridge_protocol.cc b/aos/network/message_bridge_protocol.cc
index c661c4c..c527957 100644
--- a/aos/network/message_bridge_protocol.cc
+++ b/aos/network/message_bridge_protocol.cc
@@ -9,8 +9,7 @@
 #include "aos/flatbuffers.h"
 #include "aos/network/connect_generated.h"
 
-namespace aos {
-namespace message_bridge {
+namespace aos::message_bridge {
 
 aos::FlatbufferDetachedBuffer<aos::message_bridge::Connect> MakeConnectMessage(
     const Configuration *config, const Node *my_node,
@@ -66,5 +65,4 @@
   return fbb.Release();
 }
 
-}  // namespace message_bridge
-}  // namespace aos
+}  // namespace aos::message_bridge