Convert bindings targets in mojo/mojo_services.gypi to GN.

mojo/services/test_service/BUILD.gn

Index: mojo/services/test_service/BUILD.gn
diff --git a/chrome/browser/ui/webui/omnibox/BUILD.gn b/mojo/services/test_service/BUILD.gn
similarity index 61%
copy from chrome/browser/ui/webui/omnibox/BUILD.gn
copy to mojo/services/test_service/BUILD.gn
index a2815802ef68050b0fb7a8e302ff5f73a3ad3fcc..684826ff3682736ef730fd0dd0e3ab8bca9c1431 100644
--- a/chrome/browser/ui/webui/omnibox/BUILD.gn
+++ b/mojo/services/test_service/BUILD.gn
@@ -4,9 +4,10 @@
 
 import("//mojo/public/tools/bindings/mojom.gni")
 
-# GYP version: chrome/chrome_web_ui_mojo_bindings.gyp:webui_mojo_bindings
-mojom("mojo_bindings") {
+# GYP version: mojo/mojo_services.gypi:mojo_test_service_bindings
+mojom("bindings") {
   sources = [
-    "omnibox.mojom",
+    "test_request_tracker.mojom",
+    "test_service.mojom",
   ]
 }