Make LocalFrame::DomWindow() const correct.

Before this CL, DomWindow was marked as const, but returned a mutable
LocalDOMWindow*. This CL creates two overloads of DomWindow():
- const LocalDOMWindow* DomWindow() const;
- LocalDOMWindow* DomWindow;

See: https://chromium.googlesource.com/chromium/src/+/master/styleguide/c++/c++-dos-and-donts.md#use-correctly

Change-Id: I786fc68ebe92a81ee1822ac06841aed1445889f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2592274Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Commit-Queue: Tal Pressman <talp@google.com>
Cr-Commit-Position: refs/heads/master@{#837474}

third_party/blink/renderer/core/frame/intervention.cc

@@ -19,7 +19,7 @@
 namespace blink {
 
 // static
-void Intervention::GenerateReport(const LocalFrame* frame,
+void Intervention::GenerateReport(LocalFrame* frame,
                                   const String& id,
                                   const String& message) {
   if (!frame || !frame->Client())

third_party/blink/renderer/core/frame/intervention.h

@@ -23,7 +23,7 @@ class CORE_EXPORT Intervention {
 
   // Generates a intervention report, to be routed to the Reporting API and any
   // ReportingObservers. Also sends the intervention message to the console.
-  static void GenerateReport(const LocalFrame*,
+  static void GenerateReport(LocalFrame*,
                              const String& id,
                              const String& message);
 

third_party/blink/renderer/core/frame/local_frame.cc

@@ -835,7 +835,11 @@ LocalWindowProxy* LocalFrame::WindowProxy(DOMWrapperWorld& world) {
   return To<LocalWindowProxy>(Frame::GetWindowProxy(world));
 }
 
-LocalDOMWindow* LocalFrame::DomWindow() const {
+LocalDOMWindow* LocalFrame::DomWindow() {
+  return To<LocalDOMWindow>(dom_window_.Get());
+}
+
+const LocalDOMWindow* LocalFrame::DomWindow() const {
   return To<LocalDOMWindow>(dom_window_.Get());
 }
 
@@ -2207,7 +2211,7 @@ void LocalFrame::UpdateActiveSchedulerTrackedFeatures(uint64_t features_mask) {
 }
 
 const base::UnguessableToken& LocalFrame::GetAgentClusterId() const {
-  if (LocalDOMWindow* window = DomWindow()) {
+  if (const LocalDOMWindow* window = DomWindow()) {
     return window->GetAgentClusterID();
   }
   return base::UnguessableToken::Null();

third_party/blink/renderer/core/frame/local_frame.h

@@ -222,7 +222,8 @@ class CORE_EXPORT LocalFrame final
   // corresponding method in the Frame base class to return the
   // LocalFrame-specific subclass.
   LocalWindowProxy* WindowProxy(DOMWrapperWorld&);
-  LocalDOMWindow* DomWindow() const;
+  LocalDOMWindow* DomWindow();
+  const LocalDOMWindow* DomWindow() const;
   void SetDOMWindow(LocalDOMWindow*);
   LocalFrameView* View() const override;
   Document* GetDocument() const;

third_party/blink/renderer/core/loader/image_loader.cc

@@ -558,14 +558,14 @@ void ImageLoader::DoUpdateFromElement(
     }
 
     DCHECK(document.GetFrame());
+    auto* frame = document.GetFrame();
+
     FetchParameters params(std::move(resource_request),
                            resource_loader_options);
-    ConfigureRequest(params, *element_,
-                     document.GetFrame()->GetClientHintsPreferences());
+    ConfigureRequest(params, *element_, frame->GetClientHintsPreferences());
 
     if (update_behavior != kUpdateForcedReload &&
         lazy_image_load_state_ != LazyImageLoadState::kFullImage) {
-      const auto* frame = document.GetFrame();
       if (auto* html_image = DynamicTo<HTMLImageElement>(GetElement())) {
         LoadingAttributeValue loading_attr = GetLoadingAttributeValue(
             html_image->FastGetAttribute(html_names::kLoadingAttr));

third_party/blink/renderer/core/loader/lazy_image_helper.cc

@@ -96,7 +96,7 @@ void LazyImageHelper::StopMonitoring(Element* element) {
 // static
 LazyImageHelper::Eligibility
 LazyImageHelper::DetermineEligibilityAndTrackVisibilityMetrics(
-    const LocalFrame& frame,
+    LocalFrame& frame,
     HTMLImageElement* html_image,
     const KURL& url) {
   if (!url.ProtocolIsInHTTPFamily())

third_party/blink/renderer/core/loader/lazy_image_helper.h

@@ -28,7 +28,7 @@ class LazyImageHelper final {
   static void StopMonitoring(Element* element);
 
   static Eligibility DetermineEligibilityAndTrackVisibilityMetrics(
-      const LocalFrame& frame,
+      LocalFrame& frame,
       HTMLImageElement* html_image,
       const KURL& url);