Use const ref for LocalFrame::LocalFrameRoot and FrameTree::Top

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/IntersectionGeometry.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/layout/LayoutBox.h"
@@ skipping 40 matching lines @@
   if (length.GetType() == kPercent) {
     return LayoutUnit(static_cast<int>(reference_length.ToFloat() *
                                        length.Percent() / 100.0));
   }
   DCHECK_EQ(length.GetType(), kFixed);
   return LayoutUnit(length.IntValue());
 }
 
 LayoutView* LocalRootView(Element& element) {
   LocalFrame* frame = element.GetDocument().GetFrame();
-  LocalFrame* frame_root = frame ? frame->LocalFrameRoot() : nullptr;
+  LocalFrame* frame_root = frame ? &frame->LocalFrameRoot() : nullptr;
   return frame_root ? frame_root->ContentLayoutObject() : nullptr;
 }
 
 }  // namespace
 
 IntersectionGeometry::IntersectionGeometry(Element* root,
                                            Element& target,
                                            const Vector<Length>& root_margin,
                                            bool should_report_root_bounds)
     : root_(root ? root->GetLayoutObject() : LocalRootView(target)),
@@ skipping 96 matching lines @@
   root_->GetFrameView()->MapQuadToAncestorFrameIncludingScrollOffset(
       root_rect_, root_,
       RootIsImplicit() ? nullptr : root_->GetDocument().GetLayoutView(),
       kUseTransforms | kApplyContainerFlip);
 }
 
 void IntersectionGeometry::MapIntersectionRectToTargetFrameCoordinates() {
   Document& target_document = target_->GetDocument();
   if (RootIsImplicit()) {
     LocalFrame* target_frame = target_document.GetFrame();
-    Frame* root_frame = target_frame->Tree().Top();
+    Frame& root_frame = target_frame->Tree().Top();
     LayoutSize scroll_position =
         LayoutSize(target_document.View()->GetScrollOffset());
-    if (target_frame != root_frame)
+    if (target_frame != &root_frame)
       MapRectDownToDocument(intersection_rect_, nullptr, target_document);
     intersection_rect_.Move(-scroll_position);
   } else {
     LayoutSize scroll_position =
         LayoutSize(target_document.View()->GetScrollOffset());
     MapRectUpToDocument(intersection_rect_, *root_, root_->GetDocument());
     intersection_rect_.Move(-scroll_position);
   }
 }
 
 void IntersectionGeometry::ComputeGeometry() {
   if (!CanComputeGeometry())
     return;
   ClipToRoot();
   MapTargetRectToTargetFrameCoordinates();
   if (does_intersect_)
     MapIntersectionRectToTargetFrameCoordinates();
   else
     intersection_rect_ = LayoutRect();
   // Small optimization: if we're not going to report root bounds, don't bother
   // transforming them to the frame.
   if (ShouldReportRootBounds())
     MapRootRectToRootFrameCoordinates();
 }
 
 }  // namespace blink