Merge "Use OnceKey in art.go"
diff --git a/build/art.go b/build/art.go
index 4b63829..4db8da2 100644
--- a/build/art.go
+++ b/build/art.go
@@ -253,8 +253,10 @@
 	ctx.AppendProperties(p)
 }
 
+var testMapKey = android.NewOnceKey("artTests")
+
 func testMap(config android.Config) map[string][]string {
-	return config.Once("artTests", func() interface{} {
+	return config.Once(testMapKey, func() interface{} {
 		return make(map[string][]string)
 	}).(map[string][]string)
 }