GitLab

This CL adds a |SourceType| enum to represent three different
notification item types: local media sessions, cast sessions, and
Presentation requests.
The device selector view should only show up for local media sessions.

Bug: b/161610050, 1107162
Change-Id: I45ac39af46e9aa931795fd5bb763f9c0c56c1f42
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2453891
Commit-Queue: Muyao Xu <muyaoxu@google.com>
Reviewed-by: Tommy Steimel <steimel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814914}