Fix for performance regression on high dpi devices.

Fix for performance regression on high dpi devices.

ComputedStyle::getRoundedInnerBorderFor() could generate negative
content boxes for boxes with no content and sub pixel borders that
round up (eg. 1.5px-1.99px).  Negative content boxes are illegal per
spec, and causes BoxBorderPainter::paintBorderFastPath() to bail,
and performance to be substantially degraded.

This issue would be evident on the paint-offset-changes perftest when
device pixel ratio was set to eg. 1.5.  The issue was introduced in
934becac5daa91ea979fb66e4ae21761ca11ebc9

BUG=692955
Review-Url: https://codereview.chromium.org/2782153002
Cr-Commit-Position: refs/heads/master@{#460534}
Committed: https://chromium.googlesource.com/chromium/src/+/501d97b0c948ca7c5056016083ec5279ce1edf84

[Karl Øygard, 2017-03-29 11:41:49]

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

[commit-bot: I haz the power, 2017-03-29 11:42:13]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-29 13:02:37]

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

[commit-bot: I haz the power, 2017-03-29 13:02:38]

Dry run: This issue passed the CQ dry run.

[rune, 2017-03-29 20:36:41]

rune@opera.com changed reviewers:
+ rune@opera.com

[rune, 2017-03-29 20:36:42]

lgtm

[Karl Øygard, 2017-03-29 20:45:22]

The CQ bit was checked by karlo@opera.com

[commit-bot: I haz the power, 2017-03-29 20:46:00]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-29 20:59:45]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1490820322317420, "parent_rev":
"5e6e32305efbc1d65377d8ee878d3f775a2c8366", "commit_rev":
"501d97b0c948ca7c5056016083ec5279ce1edf84"}

[commit-bot: I haz the power, 2017-03-29 21:00:37]

Description was changed from

==========
Fix for performance regression on high dpi devices.

ComputedStyle::getRoundedInnerBorderFor() could generate negative
content boxes for boxes with no content and sub pixel borders that
round up (eg. 1.5px-1.99px).  Negative content boxes are illegal per
spec, and causes BoxBorderPainter::paintBorderFastPath() to bail,
and performance to be substantially degraded.

This issue would be evident on the paint-offset-changes perftest when
device pixel ratio was set to eg. 1.5.  The issue was introduced in
934becac5daa91ea979fb66e4ae21761ca11ebc9

BUG=692955
==========

to

==========
Fix for performance regression on high dpi devices.

ComputedStyle::getRoundedInnerBorderFor() could generate negative
content boxes for boxes with no content and sub pixel borders that
round up (eg. 1.5px-1.99px).  Negative content boxes are illegal per
spec, and causes BoxBorderPainter::paintBorderFastPath() to bail,
and performance to be substantially degraded.

This issue would be evident on the paint-offset-changes perftest when
device pixel ratio was set to eg. 1.5.  The issue was introduced in
934becac5daa91ea979fb66e4ae21761ca11ebc9

BUG=692955

Review-Url: https://codereview.chromium.org/2782153002
Cr-Commit-Position: refs/heads/master@{#460534}
Committed:
https://chromium.googlesource.com/chromium/src/+/501d97b0c948ca7c5056016083ec...
==========

[commit-bot: I haz the power, 2017-03-29 21:00:38]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/501d97b0c948ca7c5056016083ec...