Spurious scrollbars should not be drawn when overflow is applied to a frame.

Spurious scrollbars should not be drawn when overflow is applied to a frame.

It doesn't really make sense to get overflow scrollbars for an iframe (the
real scrollbars are drawn within the frame, and the frame itself cannot
overflow in any useful way).

Rather than address this in the legacy compositing code, this makes the style
system prevent this nonsensical state from ever occurring, by adjusting the
overflow property to visible for all frame elements.

This matches the existing behavior of the non-composited path here: no
scrollbars are drawn in response to the 'overflow' property on a frame.

BUG=384154
TEST=LayoutTests/scrollbars/iframe-overflow-scroll-ignored.html

Committed: https://crrev.com/55de872c090f19fb64fb5e865a86c97334a4f0f0
Cr-Commit-Position: refs/heads/master@{#383855}

[jbroman, 2016-03-29 17:47:26]

jbroman@chromium.org changed reviewers:
+ leviw@chromium.org

[jbroman, 2016-03-29 17:47:26]

This way the rest of our engine won't have to deal with this state, and it's
comparable to the other adjustments to the 'overflow' property in the same
method (for marquee, textarea, etc.).

Layout test included.

[jbroman, 2016-03-29 17:47:35]

Description was changed from

==========
Spurious scrollbars should not be drawn when overflow is applied to a frame.

It doesn't really make sense to get overflow scrollbars for an iframe (the
real scrollbars are drawn within the frame, and the frame itself cannot
overflow in any useful way).

Rather than address this in the legacy compositing code, this makes the style
system prevent this nonsensical state from ever occurring, by adjusting the
overflow property to visible for all frame elements.

This matches the existing behavior of the non-composited path here: no
scrollbars are drawn in response to the 'overflow' property on a frame.

BUG=384154
==========

to

==========
Spurious scrollbars should not be drawn when overflow is applied to a frame.

It doesn't really make sense to get overflow scrollbars for an iframe (the
real scrollbars are drawn within the frame, and the frame itself cannot
overflow in any useful way).

Rather than address this in the legacy compositing code, this makes the style
system prevent this nonsensical state from ever occurring, by adjusting the
overflow property to visible for all frame elements.

This matches the existing behavior of the non-composited path here: no
scrollbars are drawn in response to the 'overflow' property on a frame.

BUG=384154
TEST=scrollbars/iframe-overflow-scroll-ignored.html
==========

[jbroman, 2016-03-29 17:47:44]

Description was changed from

==========
Spurious scrollbars should not be drawn when overflow is applied to a frame.

It doesn't really make sense to get overflow scrollbars for an iframe (the
real scrollbars are drawn within the frame, and the frame itself cannot
overflow in any useful way).

Rather than address this in the legacy compositing code, this makes the style
system prevent this nonsensical state from ever occurring, by adjusting the
overflow property to visible for all frame elements.

This matches the existing behavior of the non-composited path here: no
scrollbars are drawn in response to the 'overflow' property on a frame.

BUG=384154
TEST=scrollbars/iframe-overflow-scroll-ignored.html
==========

to

==========
Spurious scrollbars should not be drawn when overflow is applied to a frame.

It doesn't really make sense to get overflow scrollbars for an iframe (the
real scrollbars are drawn within the frame, and the frame itself cannot
overflow in any useful way).

Rather than address this in the legacy compositing code, this makes the style
system prevent this nonsensical state from ever occurring, by adjusting the
overflow property to visible for all frame elements.

This matches the existing behavior of the non-composited path here: no
scrollbars are drawn in response to the 'overflow' property on a frame.

BUG=384154
TEST=LayoutTests/scrollbars/iframe-overflow-scroll-ignored.html
==========

[leviw_travelin_and_unemployed, 2016-03-29 18:40:42]

StyleAdjuster is such a sad dumping ground :-/

I think this is fine. One nit. LGTM.

https://codereview.chromium.org/1843723002/diff/1/third_party/WebKit/Source/c...
File third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp (right):

https://codereview.chromium.org/1843723002/diff/1/third_party/WebKit/Source/c...
third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp:356:
style.setOverflowY(OverflowVisible);
Early return?

[jbroman, 2016-03-29 18:43:46]

It's a bit odd, but I think the stage is reasonably simple and understandable.
Maybe there should be a virtual Element::adjustStyle instead, but hey, it's not
that big right now.

[jbroman, 2016-03-29 18:43:52]

The CQ bit was checked by jbroman@chromium.org

[jbroman, 2016-03-29 18:43:52]

The patchset sent to the CQ was uploaded after l-g-t-m from leviw@chromium.org
Link to the patchset: https://codereview.chromium.org/1843723002/#ps20001
(title: "early-return")

[commit-bot: I haz the power, 2016-03-29 18:44:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1843723002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1843723002/20001

[commit-bot: I haz the power, 2016-03-29 23:03:23]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-03-29 23:04:24]

Description was changed from

==========
Spurious scrollbars should not be drawn when overflow is applied to a frame.

It doesn't really make sense to get overflow scrollbars for an iframe (the
real scrollbars are drawn within the frame, and the frame itself cannot
overflow in any useful way).

Rather than address this in the legacy compositing code, this makes the style
system prevent this nonsensical state from ever occurring, by adjusting the
overflow property to visible for all frame elements.

This matches the existing behavior of the non-composited path here: no
scrollbars are drawn in response to the 'overflow' property on a frame.

BUG=384154
TEST=LayoutTests/scrollbars/iframe-overflow-scroll-ignored.html
==========

to

==========
Spurious scrollbars should not be drawn when overflow is applied to a frame.

It doesn't really make sense to get overflow scrollbars for an iframe (the
real scrollbars are drawn within the frame, and the frame itself cannot
overflow in any useful way).

Rather than address this in the legacy compositing code, this makes the style
system prevent this nonsensical state from ever occurring, by adjusting the
overflow property to visible for all frame elements.

This matches the existing behavior of the non-composited path here: no
scrollbars are drawn in response to the 'overflow' property on a frame.

BUG=384154
TEST=LayoutTests/scrollbars/iframe-overflow-scroll-ignored.html

Committed: https://crrev.com/55de872c090f19fb64fb5e865a86c97334a4f0f0
Cr-Commit-Position: refs/heads/master@{#383855}
==========

[commit-bot: I haz the power, 2016-03-29 23:04:25]

Patchset 2 (id:??) landed as
https://crrev.com/55de872c090f19fb64fb5e865a86c97334a4f0f0
Cr-Commit-Position: refs/heads/master@{#383855}