[Reland] [Media Router] Enable autoresizing for the Media Router dialog for Mac.

[Reland] [Media Router] Enable autoresizing for the Media Router dialog for Mac.

This change uses an autoresizing dialog for Media Router on Macs rather than a fixed size dialog. Previously, the dialog could only autoresize on Linux and Windows.

The original CL was reverted because it depended on a patch that was reverted. It can be found here: https://codereview.chromium.org/1680533003/

BUG=508544, 580272, 580273
Review URL: https://codereview.chromium.org/1779253003

Cr-Commit-Position: refs/heads/master@{#381128}
(cherry picked from commit d903c984042f842bf73806c4c82b27b2940569c4)

Committed: https://chromium.googlesource.com/chromium/src/+/1de231ff97fb242ec205ca0abe5cfb187712ad60

[apacible, 2016-03-21 17:53:58]

Description was changed from

==========
[Reland] [Media Router] Enable autoresizing for the Media Router dialog for Mac.

This change uses an autoresizing dialog for Media Router on Macs rather than a
fixed size dialog. Previously, the dialog could only autoresize on Linux and
Windows.

The original CL was reverted because it depended on a patch that was reverted.
It can be found here: https://codereview.chromium.org/1680533003/

BUG=508544, 580272, 580273

Review URL: https://codereview.chromium.org/1779253003

Cr-Commit-Position: refs/heads/master@{#381128}
(cherry picked from commit d903c984042f842bf73806c4c82b27b2940569c4)
==========

to

==========
[Reland] [Media Router] Enable autoresizing for the Media Router dialog for Mac.

This change uses an autoresizing dialog for Media Router on Macs rather than a
fixed size dialog. Previously, the dialog could only autoresize on Linux and
Windows.

The original CL was reverted because it depended on a patch that was reverted.
It can be found here: https://codereview.chromium.org/1680533003/

BUG=508544, 580272, 580273

Review URL: https://codereview.chromium.org/1779253003

Cr-Commit-Position: refs/heads/master@{#381128}
(cherry picked from commit d903c984042f842bf73806c4c82b27b2940569c4)

Committed:
https://chromium.googlesource.com/chromium/src/+/1de231ff97fb242ec205ca0abe5c...
==========

[apacible, 2016-03-21 17:53:59]

Committed patchset #1 (id:1) manually as
1de231ff97fb242ec205ca0abe5cfb187712ad60.