Move mojo/services/public/cpp TypeConverters to mojo/converters.

mojo/BUILD.gn

Index: mojo/BUILD.gn
diff --git a/mojo/BUILD.gn b/mojo/BUILD.gn
index 7db56f74af06b23eeaaa8dda98c0d389332585e9..946e204c1a0b8544732ce72cc9acc21dfdd754d0 100644
--- a/mojo/BUILD.gn
+++ b/mojo/BUILD.gn
@@ -46,6 +46,7 @@ group("tests") {
     "//mojo/apps/js/test:mojo_apps_js_unittests",
     "//mojo/bindings/js/tests:mojo_js_unittests",
     "//mojo/common:mojo_common_unittests",
+    "//mojo/converters:converters_unittests",
     "//mojo/edk/system:mojo_message_pipe_perftests",
     "//mojo/edk/system:mojo_system_unittests",
     "//mojo/public/c/system/tests:perftests",
@@ -55,7 +56,6 @@ group("tests") {
     "//mojo/public/cpp/system/tests:mojo_public_system_unittests",
     "//mojo/public/cpp/utility/tests:mojo_public_utility_unittests",
     "//mojo/services/clipboard:mojo_clipboard_unittests",
-    "//mojo/services/public/cpp/surfaces/tests:mojo_surfaces_lib_unittests",
     "//mojo/shell:mojo_external_application_tests",
     "//mojo/shell:mojo_shell_tests",
     "//mojo/tools:message_generator",