Start archiving metrics_metadata with builds.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index b03949022493a1f23539472b6aabdf3712ea9b98..a4eb0660c9a45ed428d04351c8309d2c722f1476 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -82,6 +82,7 @@ group("gn_all") {
     "//skia:skia_unittests",
     "//sql:sql_unittests",
     "//tools/ipc_fuzzer:ipc_fuzzer_all",
+    "//tools/metrics:metrics_metadata",
     "//ui/base:ui_base_unittests",
     "//ui/gfx:gfx_unittests",
     "//url:url_unittests",