CrOS Shelf: For overflow, only forward to bubble events it can handle

Bug: 882991
Change-Id: I952c5e9ed4d2153b50fb7cfb2bc15b4f7557b9fb
Reviewed-on: https://chromium-review.googlesource.com/c/1373809
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Manu Cornet <manucornet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615982}
3 files changed