Record Cast toolbar icon state at browser initialization

Record whether or not the Cast toolbar icon is pinned whenever the
browser is initialized for a non-incognito/guest profile.

Also add openscreen-eng@ as an owner for all the Media Router
histograms.

Bug: 1023623
Change-Id: I41c5f18064e91d325326d2f08fdf085535039539
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1946693
Commit-Queue: Takumi Fujimoto <takumif@chromium.org>
Reviewed-by: Brandon Tolsch <btolsch@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Cr-Commit-Position: refs/heads/master@{#722153}
5 files changed