cc: Init PaintedScrollbarLayer::internal_contents_scale_ to 1.

cc: Init PaintedScrollbarLayer::internal_contents_scale_ to 1.

This scale is currently 0, but if a PaintedScrollbarLayerImpl ends up
in the RenderSurfaceLayerList, we'll try to get the layer's rect in
target space. Since the scale is 0 we end up dividing by 0 and get a
NaN which is bad times.

If we init this to 1 things work until the PaintedScrollbarLayer has
a chance to Update().

R=enne
BUG=497947
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Committed: https://crrev.com/69a27e219afcbb540b10e012f7e3bcad00b38e6a
Cr-Commit-Position: refs/heads/master@{#333653}

[enne (OOO), 2015-06-09 22:31:45]

lgtm

[danakj, 2015-06-09 22:39:16]

The CQ bit was checked by danakj@chromium.org

[commit-bot: I haz the power, 2015-06-09 22:41:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1172873002/1

[commit-bot: I haz the power, 2015-06-09 23:54:02]

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

[commit-bot: I haz the power, 2015-06-09 23:54:03]

Try jobs failed on following builders:
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[enne (OOO), 2015-06-09 23:56:25]

The CQ bit was checked by enne@chromium.org

[commit-bot: I haz the power, 2015-06-09 23:57:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1172873002/1

[commit-bot: I haz the power, 2015-06-10 02:11:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-10 02:12:34]

Patchset 1 (id:??) landed as
https://crrev.com/69a27e219afcbb540b10e012f7e3bcad00b38e6a
Cr-Commit-Position: refs/heads/master@{#333653}