Add default active developers into OWNERS

Bug: 33166666
Test: gerrit uploader
Change-Id: Ib584ee86db8b373bbddbf88bb336490156098690
diff --git a/OWNERS b/OWNERS
new file mode 100644
index 0000000..39b2298
--- /dev/null
+++ b/OWNERS
@@ -0,0 +1,6 @@
+# Default owners are top 3 or more active developers of the past 1 or 2 years
+# or people with more than 10 commits last year.
+# Please update this list if you find better owner candidates.
+ascull@google.com
+ngm@google.com
+wfrichar@google.com