Guard against division by zero for useless scroll bars.

Guard against division by zero for useless scroll bars.

This patch adds protection against division by zero when a scroll bar's
thumb is the full size of the track (i.e. the scroll bar is useless).

BUG=591933
Committed: https://crrev.com/5c6639a0a0b75d2696f6b3c9a5a47c8dc6096df8
Cr-Commit-Position: refs/heads/master@{#379437}

[Reilly Grant (use Gerrit), 2016-03-04 18:56:13]

reillyg@chromium.org changed reviewers:
+ sky@chromium.org

[Reilly Grant (use Gerrit), 2016-03-04 18:56:13]

Please take a look.

[sky, 2016-03-04 21:02:07]

LGTM

[Reilly Grant (use Gerrit), 2016-03-04 21:09:11]

The CQ bit was checked by reillyg@chromium.org

[commit-bot: I haz the power, 2016-03-04 21:09:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1769553003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1769553003/1

[commit-bot: I haz the power, 2016-03-04 22:40:03]

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

[commit-bot: I haz the power, 2016-03-04 22:40:04]

Try jobs failed on following builders:
  win_chromium_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[Reilly Grant (use Gerrit), 2016-03-05 02:16:26]

The CQ bit was checked by reillyg@chromium.org

[commit-bot: I haz the power, 2016-03-05 02:17:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1769553003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1769553003/1

[commit-bot: I haz the power, 2016-03-05 02:23:47]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-03-05 02:25:16]

Description was changed from

==========
Guard against division by zero for useless scroll bars.

This patch adds protection against division by zero when a scroll bar's
thumb is the full size of the track (i.e. the scroll bar is useless).

BUG=591933
==========

to

==========
Guard against division by zero for useless scroll bars.

This patch adds protection against division by zero when a scroll bar's
thumb is the full size of the track (i.e. the scroll bar is useless).

BUG=591933

Committed: https://crrev.com/5c6639a0a0b75d2696f6b3c9a5a47c8dc6096df8
Cr-Commit-Position: refs/heads/master@{#379437}
==========

[commit-bot: I haz the power, 2016-03-05 02:25:17]

Patchset 1 (id:??) landed as
https://crrev.com/5c6639a0a0b75d2696f6b3c9a5a47c8dc6096df8
Cr-Commit-Position: refs/heads/master@{#379437}