Add jwcai and tianyuj to the owner's file of libs/ui

for the development of BufferHub project. OWNERS file is out of sync.
This change syncs the file and added jwcai and tianyuj to the OWNERS.

Bug: None
Test: None
Change-Id: I817d3dc323e46aa7417a583d1faa8e0bbb87c3df
diff --git a/libs/ui/OWNERS b/libs/ui/OWNERS
index 3938e4f..97ead21 100644
--- a/libs/ui/OWNERS
+++ b/libs/ui/OWNERS
@@ -1,5 +1,7 @@
-jiyong@google.com
+lpy@google.com
+marissaw@google.com
 mathias@google.com
-olv@google.com
 romainguy@google.com
 stoza@google.com
+jwcai@google.com
+tianyuj@google.com