Fixes bug where button borders are not always painted in High DPI mode

Fixes bug where button borders are not always painted in high DPI mode.

BUG=116553
TEST=Manual

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=133459

[pkotwicz, 2012-04-17 15:02:53]

This is a short CL just fixing buttons. The problem of 1 px borders not showing
up properly is most definitely present in other controls.
This is a work around the Skia bug outlined in crbug.com/123820
Reed can you comment on the approach I am using here? I think it is OK to use
this work around wherever we use SkCanvas::drawLine or SkCanvas::drawPoint as we
don't use these methods in many places.
NativeThemeBase::DrawHorizLine & NativeThemeBase::DrawVertLine do not display
buggy behavior so they can be used as an alternative to SkCanvas::drawLine along
with an appropriate scale factor such that the output line is still 1px thick.
Rick can you comment on whether we actually want 1px lines for high dpi? The
other option is for 1px lines to scale up to 2px thick in high DPI. This is what
iframe scrollbars do right now.

[reed1, 2012-04-17 15:35:15]

I'd like to better understand the bug. At a glance this change is a little
brittle : won't work with gradients or other shaders, won't work with other
matrix ops.

[pkotwicz, 2012-04-17 21:14:10]

Changed the code to use antialiasing in drawing rounded rect.
Also changed to use of drawing round rect instead of using lines to simulate
round rect.

Not sure if there is any quality impact in drawing button background without
antialiasing and border with antialiasing.
Ie will there be cases where a bit of the background will be visible outside the
border?

[reed1, 2012-04-17 21:16:34]

Do you want to inset the rect by 1/2 of the stroke width before you draw it?
Just curious.

[reed1, 2012-04-17 21:17:09]

... or is the intention to draw a little outside and a little inside of the
rect? (in which case the code as is would be fine.)

[pkotwicz, 2012-04-18 18:19:30]

Inset border as requested.
Antialiasing both fill and border. (I think it is necessary to antialias fill)

[pkotwicz, 2012-04-21 23:12:54]

Ping

[reed1, 2012-04-23 12:08:56]

lgtm

[pkotwicz, 2012-04-23 12:53:31]

Sky for OWNERS

[sky, 2012-04-23 15:01:32]

LGTM

[commit-bot: I haz the power, 2012-04-23 15:02:14]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/pkotwicz@chromium.org/10107019/8001

[commit-bot: I haz the power, 2012-04-23 16:23:15]

Change committed as 133459