From ddb35d3718fa5fa6c32dfc93cb1acdb68ad75a90 Mon Sep 17 00:00:00 2001
From: Hiroyuki Ikezoe <hikezoe@mozilla.com>
Date: Fri, 10 May 2019 11:22:28 +0000
Subject: [PATCH] Bug 1541253 - Check PresShell::IsUnderHiddenEmbedderElement
 where we need to check CSS visibility state across the document boundary.
 r=tnikkel

Depends on D26252

Differential Revision: https://phabricator.services.mozilla.com/D26253

--HG--
extra : moz-landing-system : lando
---
 accessible/generic/Accessible.cpp | 12 ++++++++----
 layout/generic/nsFrame.cpp        |  6 ++++--
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/accessible/generic/Accessible.cpp b/accessible/generic/Accessible.cpp
index 9ab3d69cb396..ac4bc66f7206 100644
--- a/accessible/generic/Accessible.cpp
+++ b/accessible/generic/Accessible.cpp
@@ -315,13 +315,19 @@ uint64_t Accessible::VisibilityState() const {
     return states::INVISIBLE;
   }
 
-  // Walk the parent frame chain to see if there's invisible parent or the frame
-  // is in background tab.
   if (!frame->StyleVisibility()->IsVisible()) return states::INVISIBLE;
 
+  // It's invisible if the presshell is hidden by a visibility:hidden element in
+  // an ancestor document.
+  if (frame->PresShell()->IsUnderHiddenEmbedderElement()) {
+    return states::INVISIBLE;
+  }
+
   // Offscreen state if the document's visibility state is not visible.
   if (Document()->IsHidden()) return states::OFFSCREEN;
 
+  // Walk the parent frame chain to see if the frame is in background tab or
+  // scrolled out.
   nsIFrame* curFrame = frame;
   do {
     nsView* view = curFrame->GetView();
@@ -366,8 +372,6 @@ uint64_t Accessible::VisibilityState() const {
 
     if (!parentFrame) {
       parentFrame = nsLayoutUtils::GetCrossDocParentFrame(curFrame);
-      if (parentFrame && !parentFrame->StyleVisibility()->IsVisible())
-        return states::INVISIBLE;
     }
 
     curFrame = parentFrame;
diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index 638c9f2c25d1..f8b7c05e6a5c 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -393,6 +393,10 @@ bool nsIFrame::IsVisibleConsideringAncestors(uint32_t aFlags) const {
     return false;
   }
 
+  if (PresShell()->IsUnderHiddenEmbedderElement()) {
+    return false;
+  }
+
   const nsIFrame* frame = this;
   while (frame) {
     nsView* view = frame->GetView();
@@ -416,8 +420,6 @@ bool nsIFrame::IsVisibleConsideringAncestors(uint32_t aFlags) const {
         break;
       }
 
-      if (!parent->StyleVisibility()->IsVisible()) return false;
-
       frame = parent;
     }
   }