Snap the positioning area size

Snap background image positioning area size

https://codereview.chromium.org/1456813002 changed the way we handled
background image positioning in the presence of sub-pixel values, but
one value was left incorrectly unsnapped (positioning area), which
could result in backgrounds being incorrectly positioned one pixel
too far over, and in some cases clipped out entirely.

BUG=570611
Committed: https://crrev.com/4c58d12a8d30864da67caf4377d2b41ff2996dc7
Cr-Commit-Position: refs/heads/master@{#369889}

[leviw_travelin_and_unemployed, 2016-01-15 23:13:17]

Description was changed from

==========
Snap the positioning area size

BUG=570611
==========

to

==========
Snap background image positioning area size

https://codereview.chromium.org/1456813002 changed the way we handled
background image positioning in the presence of sub-pixel values, but
one value was left incorrectly unsnapped (positioning area), which
could result in backgrounds being incorrectly positioned one pixel
too far over, and in some cases clipped out entirely.

BUG=570611
==========

[leviw_travelin_and_unemployed, 2016-01-15 23:13:17]

leviw@chromium.org changed reviewers:
+ eae@chromium.org

[eae, 2016-01-15 23:26:25]

LGTM

[leviw_travelin_and_unemployed, 2016-01-15 23:42:45]

The CQ bit was checked by leviw@chromium.org

[commit-bot: I haz the power, 2016-01-15 23:43:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1583063002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1583063002/40001

[commit-bot: I haz the power, 2016-01-16 00:23:03]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-01-16 00:23:48]

Description was changed from

==========
Snap background image positioning area size

https://codereview.chromium.org/1456813002 changed the way we handled
background image positioning in the presence of sub-pixel values, but
one value was left incorrectly unsnapped (positioning area), which
could result in backgrounds being incorrectly positioned one pixel
too far over, and in some cases clipped out entirely.

BUG=570611
==========

to

==========
Snap background image positioning area size

https://codereview.chromium.org/1456813002 changed the way we handled
background image positioning in the presence of sub-pixel values, but
one value was left incorrectly unsnapped (positioning area), which
could result in backgrounds being incorrectly positioned one pixel
too far over, and in some cases clipped out entirely.

BUG=570611

Committed: https://crrev.com/4c58d12a8d30864da67caf4377d2b41ff2996dc7
Cr-Commit-Position: refs/heads/master@{#369889}
==========

[commit-bot: I haz the power, 2016-01-16 00:23:50]

Patchset 3 (id:??) landed as
https://crrev.com/4c58d12a8d30864da67caf4377d2b41ff2996dc7
Cr-Commit-Position: refs/heads/master@{#369889}