Do not allow audio to be approved by default for getDisplayMedia()

This CL changed picker UI behavior for getDisplayMedia() such that audio checkbox
is not ticked by default. This is a restriction defined in the spec.

Bug: 896333
Change-Id: I63709e895818a0cca6264cdb76528537828bc372
Reviewed-on: https://chromium-review.googlesource.com/c/1450854
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Weiyong Yao <braveyao@chromium.org>
Commit-Queue: Emircan Uysaler <emircan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630946}
7 files changed