[Media Router] Disable focus if not triggered by user.

[Media Router] Disable focus if not triggered by user.

In some cases such as page load, an unexpected focus event is triggered separately from any user input (e.g. tab or click). Disable this without disabling focus in general; focus is still needed for accessibility reasons.

BUG=593221
Review URL: https://codereview.chromium.org/1799303002

Cr-Commit-Position: refs/heads/master@{#381130}
(cherry picked from commit 280874bcce6eaa1b31d65fcdbe7f31bdfe191434)

Committed: https://chromium.googlesource.com/chromium/src/+/32ccd64cce0c370052e2ef1ba2d4421a73de2f56

[apacible, 2016-03-21 18:02:03]

Description was changed from

==========
[Media Router] Disable focus if not triggered by user.

In some cases such as page load, an unexpected focus event is triggered
separately from any user input (e.g. tab or click). Disable this without
disabling focus in general; focus is still needed for accessibility reasons.

BUG=593221

Review URL: https://codereview.chromium.org/1799303002

Cr-Commit-Position: refs/heads/master@{#381130}
(cherry picked from commit 280874bcce6eaa1b31d65fcdbe7f31bdfe191434)
==========

to

==========
[Media Router] Disable focus if not triggered by user.

In some cases such as page load, an unexpected focus event is triggered
separately from any user input (e.g. tab or click). Disable this without
disabling focus in general; focus is still needed for accessibility reasons.

BUG=593221

Review URL: https://codereview.chromium.org/1799303002

Cr-Commit-Position: refs/heads/master@{#381130}
(cherry picked from commit 280874bcce6eaa1b31d65fcdbe7f31bdfe191434)

Committed:
https://chromium.googlesource.com/chromium/src/+/32ccd64cce0c370052e2ef1ba2d4...
==========

[apacible, 2016-03-21 18:02:05]

Committed patchset #1 (id:1) manually as
32ccd64cce0c370052e2ef1ba2d4421a73de2f56.