Fix the mobile emulator to use the correct device scale when disabled.

Fix the mobile emulator to use the correct device scale when disabled.

The mobile emulator was triggering a layout before it had reapplied the
original viewport parameters when it was being disabled, which with
use-zoom-for-dsf enabled was causing the wrong viewport size to be given
to various components, like plugins and scrollbars.

BUG=628501, 628185
R=dgozman@chromium.org

Review URL: https://codereview.chromium.org/2168313002 .

Committed: https://crrev.com/d89c7a1578f9f16f6e1fa4375aab232b67fe0f9f
Cr-Original-Commit-Position: refs/heads/master@{#407294}
Cr-Commit-Position: refs/heads/master@{#407639}
(cherry picked from commit 1c78b3850f956c1507e4cdf9429652ee0ef15cb0)

Committed: https://chromium.googlesource.com/chromium/src/+/c00cb1de97175f2f023bd18b6792c9057de70dc1

[Bret, 2016-07-26 00:33:42]

Description was changed from

==========
Fix the mobile emulator to use the correct device scale when disabled.

The mobile emulator was triggering a layout before it had reapplied the
original viewport parameters when it was being disabled, which with
use-zoom-for-dsf enabled was causing the wrong viewport size to be given
to various components, like plugins and scrollbars.

BUG=628501,628185
R=dgozman@chromium.org

Review URL: https://codereview.chromium.org/2168313002 .

Committed: https://crrev.com/d89c7a1578f9f16f6e1fa4375aab232b67fe0f9f
Cr-Original-Commit-Position: refs/heads/master@{#407294}
Cr-Commit-Position: refs/heads/master@{#407639}
(cherry picked from commit 1c78b3850f956c1507e4cdf9429652ee0ef15cb0)
==========

to

==========
Fix the mobile emulator to use the correct device scale when disabled.

The mobile emulator was triggering a layout before it had reapplied the
original viewport parameters when it was being disabled, which with
use-zoom-for-dsf enabled was causing the wrong viewport size to be given
to various components, like plugins and scrollbars.

BUG=628501,628185
R=dgozman@chromium.org

Review URL: https://codereview.chromium.org/2168313002 .

Committed: https://crrev.com/d89c7a1578f9f16f6e1fa4375aab232b67fe0f9f
Cr-Original-Commit-Position: refs/heads/master@{#407294}
Cr-Commit-Position: refs/heads/master@{#407639}
(cherry picked from commit 1c78b3850f956c1507e4cdf9429652ee0ef15cb0)

Committed:
https://chromium.googlesource.com/chromium/src/+/c00cb1de97175f2f023bd18b6792...
==========

[Bret, 2016-07-26 00:33:43]

Committed patchset #1 (id:1) manually as
c00cb1de97175f2f023bd18b6792c9057de70dc1.