Add default code reviewers into OWNERS

Bug: 33166666
Test: gerrit uploader
Change-Id: If198a1c8d8423d54212ff51a227395a0b78862cd
diff --git a/OWNERS b/OWNERS
new file mode 100644
index 0000000..0d84092
--- /dev/null
+++ b/OWNERS
@@ -0,0 +1,2 @@
+szuweilin@google.com
+ycchen@google.com