Propagate viewport intersection across OOPIFs at the correct time

third_party/WebKit/Source/core/frame/RemoteFrameView.cpp

Index: third_party/WebKit/Source/core/frame/RemoteFrameView.cpp
diff --git a/third_party/WebKit/Source/core/frame/RemoteFrameView.cpp b/third_party/WebKit/Source/core/frame/RemoteFrameView.cpp
index b2bc577dee70f3ddae7748c33a02e5a006dee058..a76e9589a4839e18f3a8065f14e80cc45825f154 100644
--- a/third_party/WebKit/Source/core/frame/RemoteFrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/RemoteFrameView.cpp
@@ -59,21 +59,24 @@ void RemoteFrameView::UpdateRemoteViewportIntersection() {
   // even if there are RemoteFrame ancestors in the frame tree.
   LayoutRect rect(0, 0, frame_rect_.Width(), frame_rect_.Height());
   rect.Move(remote_frame_->OwnerLayoutObject()->ContentBoxOffset());
-  if (!remote_frame_->OwnerLayoutObject()->MapToVisualRectInAncestorSpace(
-          nullptr, rect))
-    return;
-  IntRect root_visible_rect = local_root_view->VisibleContentRect();
-  IntRect viewport_intersection(rect);
-  viewport_intersection.Intersect(root_visible_rect);
-  viewport_intersection.Move(-local_root_view->ScrollOffsetInt());
-
-  // Translate the intersection rect from the root frame's coordinate space
-  // to the remote frame's coordinate space.
-  viewport_intersection = ConvertFromRootFrame(viewport_intersection);
+  IntRect viewport_intersection;

[szager1, 2017/05/04 19:26:06]

Should this be initialized to last_viewport_intersection_?

[kenrb, 2017/05/04 19:47:10]

I don't think so. It should be zero-initialized, because it is used if the
iframe is not in the viewport (i.e. the next call to
MapToVisualRectInAncestorSpace() returns false). If the iframe has just been
scrolled out of view, we need it to be different from last_viewport_intersection
so the update is sent to the other process.

+  if (remote_frame_->OwnerLayoutObject()->MapToVisualRectInAncestorSpace(
+          nullptr, rect)) {
+    IntRect root_visible_rect = local_root_view->VisibleContentRect();
+    IntRect intersected_rect(rect);
+    intersected_rect.Intersect(root_visible_rect);
+    intersected_rect.Move(-local_root_view->ScrollOffsetInt());
+
+    // Translate the intersection rect from the root frame's coordinate space
+    // to the remote frame's coordinate space.
+    viewport_intersection = ConvertFromRootFrame(intersected_rect);
+  }
+
   if (viewport_intersection != last_viewport_intersection_) {
     remote_frame_->Client()->UpdateRemoteViewportIntersection(
         viewport_intersection);
   }
+
   last_viewport_intersection_ = viewport_intersection;
 }
 
@@ -112,8 +115,6 @@ void RemoteFrameView::FrameRectsChanged() {
   if (parent_)
     new_rect = parent_->ConvertToRootFrame(parent_->ContentsToFrame(new_rect));
   remote_frame_->Client()->FrameRectsChanged(new_rect);
-
-  UpdateRemoteViewportIntersection();
 }
 
 void RemoteFrameView::Hide() {