tree 0b92c080dec702c00e55c3a27bcb80f16b676ca2
parent c23b8bd520cb67a0f5ada377c467ca02188d85cc
author simon.fraser@apple.com <simon.fraser@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1557608332 +0000
committer simon.fraser@apple.com <simon.fraser@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1557608332 +0000

When the scroller hosting a shared layer becomes non-scrollable, content disappears
https://bugs.webkit.org/show_bug.cgi?id=197766
<rdar://problem/50695808>

Reviewed by Zalan Bujtas.

Source/WebCore:

RenderLayerCompositor::requiresOwnBackingStore() should return true for a layer that shares
its backing store. We always made backing for overlap layers, so even  if the sharing layers
have no painted content, this should rarely be a backing store memory regression.

Test: compositing/shared-backing/overflow-scroll/sharing-layer-becomes-non-scrollable.html

* rendering/RenderLayerCompositor.cpp:
(WebCore::RenderLayerCompositor::requiresOwnBackingStore const):

LayoutTests:

* compositing/shared-backing/overflow-scroll/sharing-layer-becomes-non-scrollable-expected.html: Added.
* compositing/shared-backing/overflow-scroll/sharing-layer-becomes-non-scrollable.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@245206 268f45cc-cd09-0410-ab3c-d52691b4dbfc