Use LayoutUnit in NinePieceImage drawing

Use LayoutUnit in NinePieceImage drawing

Instead of pixel snapping early on, pass through LayoutUnits and
convert directly to floats before passing values down through the
graphics context.

BUG=561519

[davve, 2015-11-27 13:31:21]

The CQ bit was checked by davve@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2015-11-27 13:33:20]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1477393003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1477393003/1

[commit-bot: I haz the power, 2015-11-27 14:39:39]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-11-27 14:39:39]

Dry run: This issue passed the CQ dry run.

[davve, 2015-11-27 14:58:45]

davve@opera.com changed reviewers:
+ eae@chromium.org, leviw@chromium.org

[davve, 2015-11-27 14:58:46]

The other plumbing part of NinePieceImageGrid and sub-pixel positioning. This
part will conflict with yours, so feel free to tell me to back off! :)

[eae, 2015-12-01 03:15:27]

I like it but please allow Levi to chime in before landing.

LGTM

[davve, 2015-12-02 08:54:55]

Description was changed from

==========
Use LayoutUnit in NinePieceImageGrid

This is in preparation for subpixel support in the rest of the
background handling code which will enable us to use LayoutSize as
container size for SVG objects. For the rest of background handling,
see bug 66498 and upcoming CLs.

BUG=561519
==========

to

==========
Use LayoutUnit in NinePieceImage drawing

Instead of pixel snapping early on, pass through LayoutUnits and
convert directly to floats before passing values down through the
graphics context.

BUG=561519
==========

[davve, 2015-12-02 10:49:41]

Patch set 2's layout test results shows how delicate this matter is. Gaps
introduced between nine piece images is bad news. Investigating.

[davve, 2015-12-02 13:51:18]

Did a quick tour in the debugger and it seemed like even though passing the
correct (float) values through the GC, the gaps didn't go away.

Might have to keep nine-piece-images pixel aligned for now.

[leviw_travelin_and_unemployed, 2015-12-02 18:27:54]

On 2015/12/02 at 13:51:18, davve wrote:
> Did a quick tour in the debugger and it seemed like even though passing the
correct (float) values through the GC, the gaps didn't go away.
> 
> Might have to keep nine-piece-images pixel aligned for now.

D'oh :( Let me know if there are more developments here.