Adjust overlay scrollbar appearance.

Adjust overlay scrollbar appearance.

- share more constants between Blink and native (Views)
- make Views paint a 1px stroke instead of a 1dip stroke, and update
  constants as per latest spec.
- fix a bug with Blink overlay scrollbars where stroke was painted on
  all sides instead of just three sides.

BUG=710550
Review-Url: https://codereview.chromium.org/2818033002
Cr-Commit-Position: refs/heads/master@{#465319}
(cherry picked from commit 41aea3751213e055f31f13d449bf21518432c6cf)

Review-Url: https://codereview.chromium.org/2830163002 .
Cr-Commit-Position: refs/branch-heads/3071@{#104}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed: https://chromium.googlesource.com/chromium/src/+/fa5b15157ef0dee2e2969115095a1a97bf0323d4

[Evan Stade, 2017-04-20 22:52:22]

Description was changed from

==========
Adjust overlay scrollbar appearance.

- share more constants between Blink and native (Views)
- make Views paint a 1px stroke instead of a 1dip stroke, and update
  constants as per latest spec.
- fix a bug with Blink overlay scrollbars where stroke was painted on
  all sides instead of just three sides.

BUG=710550

Review-Url: https://codereview.chromium.org/2818033002
Cr-Commit-Position: refs/heads/master@{#465319}
(cherry picked from commit 41aea3751213e055f31f13d449bf21518432c6cf)
==========

to

==========
Adjust overlay scrollbar appearance.

- share more constants between Blink and native (Views)
- make Views paint a 1px stroke instead of a 1dip stroke, and update
  constants as per latest spec.
- fix a bug with Blink overlay scrollbars where stroke was painted on
  all sides instead of just three sides.

BUG=710550

Review-Url: https://codereview.chromium.org/2818033002
Cr-Commit-Position: refs/heads/master@{#465319}
(cherry picked from commit 41aea3751213e055f31f13d449bf21518432c6cf)

Review-Url: https://codereview.chromium.org/2830163002 .
Cr-Commit-Position: refs/branch-heads/3071@{#104}
Cr-Branched-From:
a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed:
https://chromium.googlesource.com/chromium/src/+/fa5b15157ef0dee2e2969115095a...
==========

[Evan Stade, 2017-04-20 22:52:23]

Committed patchset #1 (id:1) manually as
fa5b15157ef0dee2e2969115095a1a97bf0323d4.