Add Go build support for GN.

mojo/go/tests/system_test.go

Index: mojo/go/tests/system_test.go
diff --git a/mojo/go/tests/system_test.go b/mojo/go/tests/system_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..8dc181f1e367e6735a99fee42021b9682cce4737
--- /dev/null
+++ b/mojo/go/tests/system_test.go
@@ -0,0 +1,19 @@
+package tests
+
+import "mojo/go/system/embedder"
+import "mojo/go/system/impl"
+import "mojo/public/go/mojo/system"
+import "testing"
+
+func Init() {
+	embedder.InitializeMojoEmbedder();
+}
+
+func TestGetTimeTicksNow(t *testing.T) {
+	Init();
+	var c system.Core = impl.GetCore();
+	x := c.GetTimeTicksNow();
+	if (x < 10) {
+		t.Error("Invalid GetTimeTicksNow return value");
+	}
+}