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/ipc_lib/index_test.cc b/aos/ipc_lib/index_test.cc
index dca75a0..8e0da6d 100644
--- a/aos/ipc_lib/index_test.cc
+++ b/aos/ipc_lib/index_test.cc
@@ -3,9 +3,7 @@
 #include "glog/logging.h"
 #include "gtest/gtest.h"
 
-namespace aos {
-namespace ipc_lib {
-namespace testing {
+namespace aos::ipc_lib::testing {
 
 class QueueIndexTest : public ::testing::Test {
  protected:
@@ -204,6 +202,4 @@
 #endif
 }
 
-}  // namespace testing
-}  // namespace ipc_lib
-}  // namespace aos
+}  // namespace aos::ipc_lib::testing