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/blob/codec_test.cc b/aos/vision/blob/codec_test.cc
index d510e58..889dfbb 100644
--- a/aos/vision/blob/codec_test.cc
+++ b/aos/vision/blob/codec_test.cc
@@ -4,8 +4,7 @@
 
 #include "gtest/gtest.h"
 
-namespace aos {
-namespace vision {
+namespace aos::vision {
 
 TEST(CodecTest, WriteRead) {
   BlobList blobl;
@@ -34,5 +33,4 @@
   EXPECT_EQ(real_len, CalculateSize(blobl));
 }
 
-}  // namespace vision
-}  // namespace aos
+}  // namespace aos::vision