bypass tab capture dialog for chrome://glic

Adds a new DISPLAY_MEDIA_TAB_CAPTURE content setting, and
enables it for chrome://glic. This content setting allows
bypassing the media selection dialog when capturing the
current tab web contents -- in the case of glic, the current
tab is actually the floating glic window.

Bug: 409118577
Change-Id: I89f3f410fdd44dbc20d4b023b313eda5b56012dd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6448791
Commit-Queue: Elad Alon <eladalon@chromium.org>
Reviewed-by: Elad Alon <eladalon@chromium.org>
Auto-Submit: Dan Harrington <harringtond@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1449885}