[SVG] Lower stroke hit testing resolution.

[SVG] Lower stroke hit testing resolution.

Skia uses a default stroke path resolution of 1/4. This
is overkill for hit-testing purposes, and can be lowered without
affecting the result accuracy significantly.

TEST=svg/hittest/*
BUG=491239
R=caryclark@google.com,fs@opera.com

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=196264

[f(malita), 2015-05-29 21:07:18]

A scale of 0.3 shows a 16-18% improvement for blink_perf.svg/SVGHitTesting
without introducing any layout test failures (those are triggered at 0.25).

[caryclark, 2015-05-29 21:11:15]

lgtm

[f(malita), 2015-05-30 16:37:15]

On 2015/05/29 21:07:18, f(malita) wrote:
> A scale of 0.3 shows a 16-18% improvement for blink_perf.svg/SVGHitTesting
> without introducing any layout test failures (those are triggered at 0.25).

Since the stroke bbox code now shares the same impl, we do get a few DRT bbox
text diffs:
https://storage.googleapis.com/chromium-layout-test-archives/linux_blink_rel/...


I don't find these particularly interesting tough, except maybe as a reminder
that ignoring the CTM causes disproportionate variance. (Unfortunately I don't
think we can realistically walk the tree and ancestor layers to compute the path
transform on each hit test.  Caching the stroke skpath may be a good option to
investigate if we decide to tackle that issue.)

[fs, 2015-06-01 07:58:32]

On 2015/05/30 16:37:15, f(malita) wrote:
> On 2015/05/29 21:07:18, f(malita) wrote:
> > A scale of 0.3 shows a 16-18% improvement for blink_perf.svg/SVGHitTesting
> > without introducing any layout test failures (those are triggered at 0.25).
> 
> Since the stroke bbox code now shares the same impl, we do get a few DRT bbox
> text diffs:
>
https://storage.googleapis.com/chromium-layout-test-archives/linux_blink_rel/...
> 
> 
> I don't find these particularly interesting tough, except maybe as a reminder
> that ignoring the CTM causes disproportionate variance. (Unfortunately I don't
> think we can realistically walk the tree and ancestor layers to compute the
path
> transform on each hit test.

In that case we'd probably want to keep track of the CTM during the tree-walk.

LGTM

[f(malita), 2015-06-01 12:55:40]

The CQ bit was checked by fmalita@chromium.org

[f(malita), 2015-06-01 12:55:41]

The patchset sent to the CQ was uploaded after l-g-t-m from caryclark@google.com
Link to the patchset: https://codereview.chromium.org/1144353005/#ps80001
(title: "+2 mac expectations")

[commit-bot: I haz the power, 2015-06-01 12:55:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1144353005/80001

[commit-bot: I haz the power, 2015-06-01 13:01:27]

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

[commit-bot: I haz the power, 2015-06-01 13:01:28]

Try jobs failed on following builders:
  blink_presubmit on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/blink_presubmit/builds/3...)

[f(malita), 2015-06-01 19:48:26]

The CQ bit was checked by fmalita@chromium.org

[commit-bot: I haz the power, 2015-06-01 19:49:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1144353005/80001

[commit-bot: I haz the power, 2015-06-01 23:35:41]

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

[commit-bot: I haz the power, 2015-06-01 23:35:43]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/6...)

[f(malita), 2015-06-01 23:56:48]

The CQ bit was checked by fmalita@chromium.org

[commit-bot: I haz the power, 2015-06-01 23:58:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1144353005/80001

[commit-bot: I haz the power, 2015-06-02 00:56:53]

Committed patchset #5 (id:80001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=196264