Intersection Observer support for OOPIF

third_party/WebKit/Source/core/layout/LayoutView.cpp

Index: third_party/WebKit/Source/core/layout/LayoutView.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutView.cpp b/third_party/WebKit/Source/core/layout/LayoutView.cpp
index 269ad5bb07092e2f6d9ab4d97ddcf9000953944d..335c1d53c765b0fc2e6587e8c4611989151fde54 100644
--- a/third_party/WebKit/Source/core/layout/LayoutView.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutView.cpp
@@ -343,6 +343,13 @@ void LayoutView::mapLocalToAncestor(const LayoutBoxModelObject* ancestor,
       transformState.move(parentDocLayoutItem.contentBoxOffset());
 
       parentDocLayoutItem.mapLocalToAncestor(ancestor, transformState, mode);
+    } else if (!document().frame()->isMainFrame()) {
+      // This is the case of a Frame with a remote parent.
+      DCHECK(!ancestor);
+      LayoutRect viewportIntersectionRect(
+          frameView()->remoteViewportIntersection());
+      transformState.move(LayoutSize(-viewportIntersectionRect.x(),
+                                     -viewportIntersectionRect.y()));
     }
   }
 }
@@ -463,16 +470,25 @@ bool LayoutView::mapToVisualRectInAncestorSpace(
     rect.move(offsetForFixedPosition(true));
 
   // Apply our transform if we have one (because of full page zooming).
-  if (!ancestor && layer() && layer()->transform())
+  if (layer() && layer()->transform())
     rect = layer()->transform()->mapRect(rect);
 
-  ASSERT(ancestor);
   if (ancestor == this)
     return true;
 
   Element* owner = document().localOwner();
-  if (!owner)
+  if (!owner) {
+    // This is the case of a Frame with a remote parent.

[dcheng, 2017/01/05 07:10:19]

While I'm OK with this patch as written, my original understanding is we'd make
these bits fairly agnostic to remote frames. Ideally, I'd like it to be so if
ancestor is nullptr, we have a generic codepath for intersecting with the
viewport that's used for local and remote frames.

Is this an impractical goal?

[szager1, 2017/01/05 20:25:22]

+1, it should be straightforward to add something to FrameView for this,
something like:

Element* owner = document().localOwner();
if (!owner)
  return frameView()->mapToVisualRectInTopFrameSpace(rect);

[kenrb, 2017/01/09 19:31:20]

Done. I similarly moved the logic out of mapLocalToAncestor, above. Please let
me know if there is any concern with that.

+    if (!document().frame()->isMainFrame()) {
+      DCHECK(!ancestor);
+      LayoutRect viewportIntersectionRect(
+          frameView()->remoteViewportIntersection());
+      rect.intersect(viewportIntersectionRect);
+      if (rect.isEmpty())
+        return false;
+    }
     return true;
+  }
 
   if (LayoutBox* obj = owner->layoutBox()) {
     if (!(mode & InputIsInFrameCoordinates)) {