ExclusiveAccessBubbleViews: Use BoxLayout instead of GridLayout.

ExclusiveAccessBubbleViews: Use BoxLayout instead of GridLayout.

BoxLayout is more appropriate, and does not suffer the 'invisible
children still take up space' issue of GridLayout (crbug.com/548551).
(There is a work-around for this issue with Label, but not with other
view types which we'll need in the future.)

Removed the code for Label and ButtonView to make their GetPreferredSize
return 0 when hidden (no longer necessary).

This CL should not have any observable effect.

BUG=352425
Committed: https://crrev.com/0c1375df4d18383c937632d9b126e6a118096c63
Cr-Commit-Position: refs/heads/master@{#358238}

[Matt Giuca, 2015-11-05 06:07:44]

mgiuca@chromium.org changed reviewers:
+ msw@chromium.org

[Matt Giuca, 2015-11-05 06:07:45]

Note: Following from a discussion with sadrul@ on
https://codereview.chromium.org/1422703004/; it may be good to fix GridLayout so
that it respects its children's visibility. But I don't want to block on this,
and BoxLayout is more appropriate in this case anyway, so just switching fully
over to BoxLayout.

[msw, 2015-11-05 18:54:28]

It'd be nice to see some before/after pics to ensure the layout remains as
expected, but lgtm.

[Matt Giuca, 2015-11-06 01:56:11]

On 2015/11/05 18:54:28, msw wrote:
> It'd be nice to see some before/after pics to ensure the layout remains as
> expected, but lgtm.

Screenshots attached on http://crbug.com/352425#c97.

[Matt Giuca, 2015-11-06 01:56:14]

The CQ bit was checked by mgiuca@chromium.org

[commit-bot: I haz the power, 2015-11-06 01:56:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1410413007/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1410413007/1

[commit-bot: I haz the power, 2015-11-06 02:34:38]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-06 02:35:41]

Patchset 1 (id:??) landed as
https://crrev.com/0c1375df4d18383c937632d9b126e6a118096c63
Cr-Commit-Position: refs/heads/master@{#358238}