Implement event sender service for testing

sky/services/testing/BUILD.gn

Index: sky/services/testing/BUILD.gn
diff --git a/services/http_server/public/BUILD.gn b/sky/services/testing/BUILD.gn
similarity index 70%
copy from services/http_server/public/BUILD.gn
copy to sky/services/testing/BUILD.gn
index 59dcd16f99f21b0e0cd427264c51d5dfbf05bb50..23af71237c303d94d8f841944389a0fcd3e3f50c 100644
--- a/services/http_server/public/BUILD.gn
+++ b/sky/services/testing/BUILD.gn
@@ -4,10 +4,8 @@
 
 import("//mojo/public/tools/bindings/mojom.gni")
 
-mojom("public") {
+mojom("bindings") {
   sources = [
-    "http_request.mojom",
-    "http_response.mojom",
-    "http_server.mojom",
+    "test_harness.mojom",
   ]
 }