- supporting appending new data instead of simply replacing the current set
- fix issue when not filtering out groups on initial loading

Change-Id: I77d508e644b247fa236ea64ef919639cac6ee425

NOTRY=true

Change-Id: I77d508e644b247fa236ea64ef919639cac6ee425
Reviewed-on: https://chromium-review.googlesource.com/451276
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43685}