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

@@ -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;

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;
     }
   }