Support edge-inclusive intersections in mapToVisibleRectInAncestorSpace

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 f1ecdfa63692fe8c7e2134668be174c57723f868..918fa9b335ae02445cced73853f6cf46af185453 100644
--- a/third_party/WebKit/Source/core/layout/LayoutView.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutView.cpp
@@ -475,15 +475,15 @@ void LayoutView::invalidatePaintForViewAndCompositedLayers()
         compositor()->fullyInvalidatePaint();
 }
 
-void LayoutView::mapToVisibleRectInAncestorSpace(const LayoutBoxModelObject* ancestor, LayoutRect& rect, const PaintInvalidationState* invalidationState) const
+bool LayoutView::mapToVisibleRectInAncestorSpace(const LayoutBoxModelObject* ancestor, LayoutRect& rect, const PaintInvalidationState* invalidationState, int flags) const
 {
-    mapToVisibleRectInAncestorSpace(ancestor, rect, IsNotFixedPosition, invalidationState);
+    return mapToVisibleRectInAncestorSpace(ancestor, rect, IsNotFixedPosition, invalidationState, flags);
 }
 
-void LayoutView::mapToVisibleRectInAncestorSpace(const LayoutBoxModelObject* ancestor, LayoutRect& rect, ViewportConstrainedPosition viewportConstraint, const PaintInvalidationState* state) const
+bool LayoutView::mapToVisibleRectInAncestorSpace(const LayoutBoxModelObject* ancestor, LayoutRect& rect, ViewportConstrainedPosition viewportConstraint, const PaintInvalidationState* state, int flags) const
 {
     if (document().printing())
-        return;
+        return true;
 
     if (style()->isFlippedBlocksWritingMode()) {
         // We have to flip by hand since the view's logical height has not been determined.  We
@@ -502,17 +502,22 @@ void LayoutView::mapToVisibleRectInAncestorSpace(const LayoutBoxModelObject* anc
 
     ASSERT(ancestor);
     if (ancestor == this)
-        return;
+        return true;
 
     Element* owner = document().ownerElement();
     if (!owner)
-        return;
+        return true;
 
     if (LayoutBox* obj = owner->layoutBox()) {
         if (!state || !state->viewClippingAndScrollOffsetDisabled()) {
             // Intersect the viewport with the paint invalidation rect.
             LayoutRect viewRectangle = viewRect();
-            rect.intersect(viewRectangle);
+            if (flags & EdgeInclusive) {
+                if (!rect.inclusiveIntersect(viewRectangle))
+                    return false;
+            } else {
+                rect.intersect(viewRectangle);

[chrishtr, 2016/03/22 17:25:49]

return false here if it's empty? Early out code?

+            }
 
             // Adjust for scroll offset of the view.
             rect.moveBy(-viewRectangle.location());
@@ -520,8 +525,10 @@ void LayoutView::mapToVisibleRectInAncestorSpace(const LayoutBoxModelObject* anc
 
         // Adjust for frame border.
         rect.move(obj->contentBoxOffset());
-        obj->mapToVisibleRectInAncestorSpace(ancestor, rect, 0);
+        return obj->mapToVisibleRectInAncestorSpace(ancestor, rect, 0, flags);
     }
+
+    return true;
 }
 
 void LayoutView::adjustViewportConstrainedOffset(LayoutRect& rect, ViewportConstrainedPosition viewportConstraint) const