Add default code reviewers into OWNERS

Bug: 33166666
Test: gerrit uploader
Change-Id: I54d80668822c92f055f200f228fd7972297c2d44
diff --git a/OWNERS b/OWNERS
new file mode 100644
index 0000000..30f1999
--- /dev/null
+++ b/OWNERS
@@ -0,0 +1,2 @@
+chh@google.com
+enh@google.com