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

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

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Simon Hausmann <hausmann@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  *                     2001 George Staikos <staikos@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov <ap@nypop.com>
@@ skipping 549 matching lines @@
   return LayoutViewItem(ContentLayoutObject());
 }
 
 void LocalFrame::DidChangeVisibilityState() {
   if (GetDocument())
     GetDocument()->DidChangeVisibilityState();
 
   Frame::DidChangeVisibilityState();
 }
 
-LocalFrame* LocalFrame::LocalFrameRoot() {
-  LocalFrame* cur_frame = this;
+LocalFrame& LocalFrame::LocalFrameRoot() const {
+  const LocalFrame* cur_frame = this;
   while (cur_frame && cur_frame->Tree().Parent() &&
          cur_frame->Tree().Parent()->IsLocalFrame())
     cur_frame = ToLocalFrame(cur_frame->Tree().Parent());
 
-  return cur_frame;
+  return const_cast<LocalFrame&>(*cur_frame);
 }
 
 bool LocalFrame::IsCrossOriginSubframe() const {
   const SecurityOrigin* security_origin =
       GetSecurityContext()->GetSecurityOrigin();
-  Frame* top = Tree().Top();
-  return top && !security_origin->CanAccess(
-                    top->GetSecurityContext()->GetSecurityOrigin());
+  return !security_origin->CanAccess(
+      Tree().Top().GetSecurityContext()->GetSecurityOrigin());
 }
 
 void LocalFrame::SetPrinting(bool printing,
                              const FloatSize& page_size,
                              const FloatSize& original_page_size,
                              float maximum_shrink_ratio) {
   // In setting printing, we should not validate resources already cached for
   // the document.  See https://bugs.webkit.org/show_bug.cgi?id=43704
   ResourceCacheValidationSuppressor validation_suppressor(
       GetDocument()->Fetcher());
@@ skipping 299 matching lines @@
       navigation_disable_count_(0),
       page_zoom_factor_(ParentPageZoomFactor(this)),
       text_zoom_factor_(ParentTextZoomFactor(this)),
       in_view_source_mode_(false),
       interface_provider_(interface_provider),
       interface_registry_(interface_registry) {
   if (IsLocalRoot()) {
     instrumenting_agents_ = new CoreProbeSink();
     performance_monitor_ = new PerformanceMonitor(this);
   } else {
-    instrumenting_agents_ = LocalFrameRoot()->instrumenting_agents_;
-    performance_monitor_ = LocalFrameRoot()->performance_monitor_;
+    instrumenting_agents_ = LocalFrameRoot().instrumenting_agents_;
+    performance_monitor_ = LocalFrameRoot().performance_monitor_;
   }
 }
 
 WebFrameScheduler* LocalFrame::FrameScheduler() {
   return frame_scheduler_.get();
 }
 
 void LocalFrame::ScheduleVisualUpdateUnlessThrottled() {
   if (ShouldThrottleRendering())
     return;
   GetPage()->Animator().ScheduleVisualUpdate(this);
 }
 
 LocalFrameClient* LocalFrame::Client() const {
   return static_cast<LocalFrameClient*>(Frame::Client());
 }
 
 ContentSettingsClient* LocalFrame::GetContentSettingsClient() {
   return Client() ? &Client()->GetContentSettingsClient() : nullptr;
 }
 
 PluginData* LocalFrame::GetPluginData() const {
   if (!Loader().AllowPlugins(kNotAboutToInstantiatePlugin))
     return nullptr;
   return GetPage()->GetPluginData(
-      Tree().Top()->GetSecurityContext()->GetSecurityOrigin());
+      Tree().Top().GetSecurityContext()->GetSecurityOrigin());
 }
 
 DEFINE_WEAK_IDENTIFIER_MAP(LocalFrame);
 
 FrameNavigationDisabler::FrameNavigationDisabler(LocalFrame& frame)
     : frame_(&frame) {
   frame_->DisableNavigation();
 }
 
 FrameNavigationDisabler::~FrameNavigationDisabler() {
   frame_->EnableNavigation();
 }
 
 ScopedFrameBlamer::ScopedFrameBlamer(LocalFrame* frame) : frame_(frame) {
   if (frame_ && frame_->Client() && frame_->Client()->GetFrameBlameContext())
     frame_->Client()->GetFrameBlameContext()->Enter();
 }
 
 ScopedFrameBlamer::~ScopedFrameBlamer() {
   if (frame_ && frame_->Client() && frame_->Client()->GetFrameBlameContext())
     frame_->Client()->GetFrameBlameContext()->Leave();
 }
 
 }  // namespace blink