Allow layers that need squashing to draw into the squashing layer in some cases.

Allow layers that need squashing to draw into the squashing layer in some cases.

In particular, allow a layer L to squash if their clipping
ancestor differs from the squashing owner, but the clipping
ancestor for L is a descendant of a layer that does squash
into the squashing owner.

BUG=368410
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=173690

[abarth-chromium, 2014-05-05 21:37:39]

https://codereview.chromium.org/264013002/diff/20001/Source/core/rendering/Re...
File Source/core/rendering/RenderLayer.cpp (right):

https://codereview.chromium.org/264013002/diff/20001/Source/core/rendering/Re...
Source/core/rendering/RenderLayer.cpp:1141: for (const RenderLayer* curr = this;
curr; curr = curr->parent()) {
Is this the right parent chain to walk?  I would have expected you to walk the
parents in the Stacking tree...

[chrishtr, 2014-05-05 21:58:50]

https://codereview.chromium.org/264013002/diff/20001/Source/core/rendering/Re...
File Source/core/rendering/RenderLayer.cpp (right):

https://codereview.chromium.org/264013002/diff/20001/Source/core/rendering/Re...
Source/core/rendering/RenderLayer.cpp:1141: for (const RenderLayer* curr = this;
curr; curr = curr->parent()) {
On 2014/05/05 21:37:40, abarth wrote:
> Is this the right parent chain to walk?  I would have expected you to walk the
> parents in the Stacking tree...

Right this is I think the issue with this CL.

[Ian Vollick, 2014-05-08 20:56:18]

This seems reasonable. lgtm if the bots are happy.

https://codereview.chromium.org/264013002/diff/150001/Source/core/rendering/c...
File Source/core/rendering/compositing/CompositedLayerMapping.cpp (right):

https://codereview.chromium.org/264013002/diff/150001/Source/core/rendering/c...
Source/core/rendering/compositing/CompositedLayerMapping.cpp:1864:
ClipRectsContext clipRectsContext(ancestorPaintInfo->renderLayer,
TemporaryClipRects);
This could hurt perf. Even if we don't figure out how to cache in this CL, it'd
be worth adding a comment here mentioning that this is a bit of code to optimize
in future.

[chrishtr, 2014-05-08 20:58:15]

https://codereview.chromium.org/264013002/diff/150001/Source/core/rendering/c...
File Source/core/rendering/compositing/CompositedLayerMapping.cpp (right):

https://codereview.chromium.org/264013002/diff/150001/Source/core/rendering/c...
Source/core/rendering/compositing/CompositedLayerMapping.cpp:1864:
ClipRectsContext clipRectsContext(ancestorPaintInfo->renderLayer,
TemporaryClipRects);
On 2014/05/08 20:56:19, Ian Vollick wrote:
> This could hurt perf. Even if we don't figure out how to cache in this CL,
it'd
> be worth adding a comment here mentioning that this is a bit of code to
optimize
> in future. 

Added a FIXME.

[chrishtr, 2014-05-08 20:59:12]

The CQ bit was checked by chrishtr@chromium.org

[commit-bot: I haz the power, 2014-05-08 21:00:59]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/chrishtr@chromium.org/264013002/170001

[commit-bot: I haz the power, 2014-05-08 22:18:11]

Change committed as 173690