GitLab

This patch fixes some issues with tab sink availability by modifying the
MediaRouterMojoImpl to have a single SinksQuery for all tabs,
tabs_sinks_query_, instead of registering a unique sinks query for each
unique tab media source id.

In places where a media source id is expected, specifically for the
media router providers themselves, a hardcoded media source id for tab 0
is passed.

Bug: 1013769, b/154115531
Change-Id: I8cdb05fba9aa813153e66bf3af8e5f3d17581903
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2200015
Commit-Queue: Jordan Bayles <jophba@chromium.org>
Reviewed-by: Takumi Fujimoto <takumif@chromium.org>
Cr-Commit-Position: refs/heads/master@{#771963}