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_client.cc b/aos/network/message_bridge_client.cc
index ef727eb..4a1992a 100644
--- a/aos/network/message_bridge_client.cc
+++ b/aos/network/message_bridge_client.cc
@@ -12,8 +12,7 @@
     wants_sctp_authentication, false,
     "When set, try to use SCTP authentication if provided by the kernel");
 
-namespace aos {
-namespace message_bridge {
+namespace aos::message_bridge {
 
 using ::aos::util::ReadFileToVecOrDie;
 
@@ -42,8 +41,7 @@
   return EXIT_SUCCESS;
 }
 
-}  // namespace message_bridge
-}  // namespace aos
+}  // namespace aos::message_bridge
 
 int main(int argc, char **argv) {
   aos::InitGoogle(&argc, &argv);