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/vision/events/udp_test.cc b/aos/vision/events/udp_test.cc
index 33fb4d6..506be28 100644
--- a/aos/vision/events/udp_test.cc
+++ b/aos/vision/events/udp_test.cc
@@ -2,8 +2,7 @@
 
 #include "gtest/gtest.h"
 
-namespace aos {
-namespace events {
+namespace aos::events {
 
 TEST(UDPTest, SendRecv) {
   RXUdpSocket rx(1109);
@@ -19,5 +18,4 @@
   EXPECT_EQ(txdata[3], rxdata[3]);
 }
 
-}  // namespace events
-}  // namespace aos
+}  // namespace aos::events