Make some |Event| arguments |const|

Make |Event| arguments of the following functions |const|:
- Node::DispatchSimulatedClick()
- HTMLFormElement::SubmitImplicitly()
- HTMLFormElement::PrepareForSubmission()
- HTMLFormElement::ScheduleFormSubmission()
- SelectType::DefaultEventHandler()

This CL has no behavior changes.

Change-Id: I91c233a6dead779f771ddeea357bad3f91a145f0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2060214Reviewed-by: Koji Ishii <kojii@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742072}

third_party/blink/renderer/core/dom/node.cc

@@ -2939,7 +2939,7 @@ DispatchEventResult Node::DispatchDOMActivateEvent(int detail,
   return EventTarget::GetDispatchEventResult(event);
 }
 
-void Node::DispatchSimulatedClick(Event* underlying_event,
+void Node::DispatchSimulatedClick(const Event* underlying_event,
                                   SimulatedClickMouseEventOptions event_options,
                                   SimulatedClickCreationScope scope) {
   if (auto* element = IsElementNode() ? To<Element>(this) : parentElement()) {

third_party/blink/renderer/core/dom/node.h

@@ -857,7 +857,7 @@ class CORE_EXPORT Node : public EventTarget {
   DispatchEventResult DispatchDOMActivateEvent(int detail,
                                                Event& underlying_event);
 
-  void DispatchSimulatedClick(Event* underlying_event,
+  void DispatchSimulatedClick(const Event* underlying_event,
                               SimulatedClickMouseEventOptions = kSendNoEvents,
                               SimulatedClickCreationScope =
                                   SimulatedClickCreationScope::kFromUserAgent);

third_party/blink/renderer/core/html/forms/html_form_element.cc

@@ -181,7 +181,7 @@ HTMLElement* HTMLFormElement::item(unsigned index) {
   return elements()->item(index);
 }
 
-void HTMLFormElement::SubmitImplicitly(Event& event,
+void HTMLFormElement::SubmitImplicitly(const Event& event,
                                        bool from_implicit_submission_trigger) {
   int submission_trigger_count = 0;
   bool seen_default_button = false;
@@ -251,7 +251,7 @@ bool HTMLFormElement::ValidateInteractively() {
 }
 
 void HTMLFormElement::PrepareForSubmission(
-    Event* event,
+    const Event* event,
     HTMLFormControlElement* submit_button) {
   LocalFrame* frame = GetDocument().GetFrame();
   if (!frame || is_submitting_ || in_user_js_submit_event_)
@@ -377,7 +377,7 @@ void HTMLFormElement::SubmitDialog(FormSubmission* form_submission) {
 }
 
 void HTMLFormElement::ScheduleFormSubmission(
-    Event* event,
+    const Event* event,
     HTMLFormControlElement* submit_button) {
   LocalFrameView* view = GetDocument().View();
   LocalFrame* frame = GetDocument().GetFrame();

third_party/blink/renderer/core/html/forms/html_form_element.h

@@ -71,13 +71,14 @@ class CORE_EXPORT HTMLFormElement final : public HTMLElement {
   void Disassociate(HTMLImageElement&);
   void DidAssociateByParser();
 
-  void PrepareForSubmission(Event*, HTMLFormControlElement* submit_button);
+  void PrepareForSubmission(const Event*,
+                            HTMLFormControlElement* submit_button);
   void submitFromJavaScript();
   void requestSubmit(ExceptionState& exception_state);
   void requestSubmit(HTMLElement* submitter, ExceptionState& exception_state);
   void reset();
 
-  void SubmitImplicitly(Event&, bool from_implicit_submission_trigger);
+  void SubmitImplicitly(const Event&, bool from_implicit_submission_trigger);
 
   String GetName() const;
 
@@ -133,7 +134,8 @@ class CORE_EXPORT HTMLFormElement final : public HTMLElement {
   }
 
   void SubmitDialog(FormSubmission*);
-  void ScheduleFormSubmission(Event*, HTMLFormControlElement* submit_button);
+  void ScheduleFormSubmission(const Event*,
+                              HTMLFormControlElement* submit_button);
 
   void CollectListedElements(Node& root, ListedElement::List&) const;
   void CollectImageElements(Node& root, HeapVector<Member<HTMLImageElement>>&);

third_party/blink/renderer/core/html/forms/select_type.cc

@@ -64,7 +64,7 @@ class MenuListSelectType final : public SelectType {
  public:
   explicit MenuListSelectType(HTMLSelectElement& select) : SelectType(select) {}
 
-  bool DefaultEventHandler(Event& event) override;
+  bool DefaultEventHandler(const Event& event) override;
   void DidSelectOption(HTMLOptionElement* element,
                        HTMLSelectElement::SelectOptionFlags flags,
                        bool should_update_popup) override;
@@ -83,7 +83,7 @@ class MenuListSelectType final : public SelectType {
   bool has_updated_menulist_active_option_ = false;
 };
 
-bool MenuListSelectType::DefaultEventHandler(Event& event) {
+bool MenuListSelectType::DefaultEventHandler(const Event& event) {
   // We need to make the layout tree up-to-date to have GetLayoutObject() give
   // the correct result below. An author event handler may have set display to
   // some element to none which will cause a layout tree detach.
@@ -167,7 +167,7 @@ bool MenuListSelectType::DefaultEventHandler(Event& event) {
       return true;
     }
 
-    auto& key_event = ToKeyboardEvent(event);
+    const auto& key_event = ToKeyboardEvent(event);
     if (select_->ShouldOpenPopupForKeyPressEvent(key_event))
       return select_->HandlePopupOpenKeyboardEvent(event);
 
@@ -180,7 +180,7 @@ bool MenuListSelectType::DefaultEventHandler(Event& event) {
     return false;
   }
 
-  auto* mouse_event = DynamicTo<MouseEvent>(event);
+  const auto* mouse_event = DynamicTo<MouseEvent>(event);
   if (event.type() == event_type_names::kMousedown && mouse_event &&
       mouse_event->button() ==
           static_cast<int16_t>(WebPointerProperties::Button::kLeft)) {
@@ -340,11 +340,11 @@ void MenuListSelectType::DidUpdateActiveOption(HTMLOptionElement* option) {
 class ListBoxSelectType final : public SelectType {
  public:
   explicit ListBoxSelectType(HTMLSelectElement& select) : SelectType(select) {}
-  bool DefaultEventHandler(Event& event) override;
+  bool DefaultEventHandler(const Event& event) override;
 };
 
-bool ListBoxSelectType::DefaultEventHandler(Event& event) {
-  auto* mouse_event = DynamicTo<MouseEvent>(event);
+bool ListBoxSelectType::DefaultEventHandler(const Event& event) {
+  const auto* mouse_event = DynamicTo<MouseEvent>(event);
   if (event.type() == event_type_names::kGesturetap && event.IsGestureEvent()) {
     select_->focus();
     // Calling focus() may cause us to lose our layoutObject or change the
@@ -353,7 +353,7 @@ bool ListBoxSelectType::DefaultEventHandler(Event& event) {
       return false;
 
     // Convert to coords relative to the list box if needed.
-    auto& gesture_event = ToGestureEvent(event);
+    const auto& gesture_event = ToGestureEvent(event);
     if (HTMLOptionElement* option = EventTargetOption(gesture_event)) {
       if (!select_->IsDisabledFormControl()) {
         select_->UpdateSelectedState(option, true, gesture_event.shiftKey());
@@ -445,7 +445,7 @@ bool ListBoxSelectType::DefaultEventHandler(Event& event) {
   }
 
   if (event.type() == event_type_names::kKeydown) {
-    auto* keyboard_event = ToKeyboardEventOrNull(event);
+    const auto* keyboard_event = ToKeyboardEventOrNull(event);
     if (!keyboard_event)
       return false;
     const String& key = keyboard_event->key();

third_party/blink/renderer/core/html/forms/select_type.h

@@ -21,7 +21,7 @@ class SelectType : public GarbageCollected<SelectType> {
   virtual void Trace(Visitor* visitor);
 
   // Returns true if the event is handled.
-  virtual bool DefaultEventHandler(Event& event) = 0;
+  virtual bool DefaultEventHandler(const Event& event) = 0;
 
   virtual void DidSelectOption(HTMLOptionElement* element,
                                HTMLSelectElement::SelectOptionFlags flags,