Reparented overflow controls host layer must account for scrolling.

Reparented overflow controls host layer must account for scrolling.

The math to position the host layer does not account for scrolling, and
this causes incorrect behavior with nested scrollers.

BUG=None

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=185149

[Ian Vollick, 2014-11-10 14:27:24]

vollick@chromium.org changed reviewers:
+ chrishtr@chromium.org

[Ian Vollick, 2014-11-11 17:20:56]

On 2014/11/10 14:27:25, vollick wrote:

Ping

[chrishtr, 2014-11-11 17:25:13]

No bug?

https://codereview.chromium.org/667913003/diff/20001/LayoutTests/compositing/...
File LayoutTests/compositing/scrollbars/nested-overlay-scrollbars.html (right):

https://codereview.chromium.org/667913003/diff/20001/LayoutTests/compositing/...
LayoutTests/compositing/scrollbars/nested-overlay-scrollbars.html:51:
document.getElementById("outer").scrollTop = 600;
Scroll to 700 so we can see half of the gray?

[Ian Vollick, 2014-11-11 20:28:31]

Nope, no bug. I happened to run across this issue when putting a demo together
and put this fix together.

https://codereview.chromium.org/667913003/diff/20001/LayoutTests/compositing/...
File LayoutTests/compositing/scrollbars/nested-overlay-scrollbars.html (right):

https://codereview.chromium.org/667913003/diff/20001/LayoutTests/compositing/...
LayoutTests/compositing/scrollbars/nested-overlay-scrollbars.html:51:
document.getElementById("outer").scrollTop = 600;
On 2014/11/11 17:25:13, chrishtr wrote:
> Scroll to 700 so we can see half of the gray?

Scrolling to 700 doesn't scroll you any further in this case. It's the outer
scroller that's being affected and it's already at the bottom. When this test is
broken what you see is that the scrollbars on the inner scroller have shifted
right off it.

[chrishtr, 2014-11-11 21:11:05]

lgtm

[Ian Vollick, 2014-11-11 22:46:32]

The CQ bit was checked by vollick@chromium.org

[commit-bot: I haz the power, 2014-11-11 22:46:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/667913003/20001

[commit-bot: I haz the power, 2014-11-11 23:03:26]

Committed patchset #2 (id:20001) as 185149