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

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

 // Copyright 2014 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/frame/RemoteFrameView.h"
 
 #include "core/dom/IntersectionObserverEntry.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/RemoteFrame.h"
@@ skipping 29 matching lines @@
   RemoteFrameView* view = new RemoteFrameView(remote_frame);
   view->Show();
   return view;
 }
 
 void RemoteFrameView::UpdateRemoteViewportIntersection() {
   if (!remote_frame_->OwnerLayoutObject())
     return;
 
   FrameView* local_root_view =
-      ToLocalFrame(remote_frame_->Tree().Parent())->LocalFrameRoot()->View();
+      ToLocalFrame(remote_frame_->Tree().Parent())->LocalFrameRoot().View();
   if (!local_root_view)
     return;
 
   // Start with rect in remote frame's coordinate space. Then
   // mapToVisualRectInAncestorSpace will move it to the local root's coordinate
   // space and account for any clip from containing elements such as a
   // scrollable div. Passing nullptr as an argument to
   // mapToVisualRectInAncestorSpace causes it to be clipped to the viewport,
   // even if there are RemoteFrame ancestors in the frame tree.
   LayoutRect rect(0, 0, frame_rect_.Width(), frame_rect_.Height());
@@ skipping 87 matching lines @@
 
   return parent_rect;
 }
 
 DEFINE_TRACE(RemoteFrameView) {
   visitor->Trace(remote_frame_);
   visitor->Trace(parent_);
 }
 
 }  // namespace blink