Use Event& instead of Event* as a parameter of PreDispatchEventHandler

When PreDispatchEventHandler is called, Event object was passed as a
parameter. and it is never nullptr.
so it can be changed to reference instead of pointer.

Bug: 871637
Change-Id: Id8f1b05c51024e6418eaf2e7517f6dfb2ec70699
Reviewed-on: https://chromium-review.googlesource.com/1179520Reviewed-by: Hayato Ito <hayato@chromium.org>
Commit-Queue: Hwanseung Lee <hs1217.lee@samsung.com>
Cr-Commit-Position: refs/heads/master@{#584358}

third_party/blink/renderer/core/dom/events/event_dispatcher.cc

@@ -206,7 +206,7 @@ inline EventDispatchContinuation EventDispatcher::DispatchEventPreProcess(
   // legacy-pre-activation behavior.
   if (activation_target) {
     pre_dispatch_event_handler_result =
-        activation_target->PreDispatchEventHandler(event_.Get());
+        activation_target->PreDispatchEventHandler(*event_);
   }
   return (event_->GetEventPath().IsEmpty() || event_->PropagationStopped())
              ? kDoneDispatching

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

@@ -771,7 +771,7 @@ class CORE_EXPORT Node : public EventTarget {
   // Handlers to do/undo actions on the target node before an event is
   // dispatched to it and after the event has been dispatched.  The data pointer
   // is handed back by the preDispatch and passed to postDispatch.
-  virtual EventDispatchHandlingState* PreDispatchEventHandler(Event*) {
+  virtual EventDispatchHandlingState* PreDispatchEventHandler(Event&) {
     return nullptr;
   }
   virtual void PostDispatchEventHandler(Event*, EventDispatchHandlingState*) {}

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

@@ -1230,16 +1230,16 @@ void HTMLInputElement::SetValueFromRenderer(const String& value) {
 }
 
 EventDispatchHandlingState* HTMLInputElement::PreDispatchEventHandler(
-    Event* event) {
-  if (event->type() == EventTypeNames::textInput &&
-      input_type_view_->ShouldSubmitImplicitly(*event)) {
-    event->stopPropagation();
+    Event& event) {
+  if (event.type() == EventTypeNames::textInput &&
+      input_type_view_->ShouldSubmitImplicitly(event)) {
+    event.stopPropagation();
     return nullptr;
   }
-  if (event->type() != EventTypeNames::click)
+  if (event.type() != EventTypeNames::click)
     return nullptr;
-  if (!event->IsMouseEvent() ||
-      ToMouseEvent(event)->button() !=
+  if (!event.IsMouseEvent() ||
+      ToMouseEvent(event).button() !=
           static_cast<short>(WebPointerProperties::Button::kLeft))
     return nullptr;
   return input_type_view_->WillDispatchClick();

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

@@ -361,7 +361,7 @@ class CORE_EXPORT HTMLInputElement
   void ResetImpl() final;
   bool SupportsAutofocus() const final;
 
-  EventDispatchHandlingState* PreDispatchEventHandler(Event*) final;
+  EventDispatchHandlingState* PreDispatchEventHandler(Event&) final;
   void PostDispatchEventHandler(Event*, EventDispatchHandlingState*) final;
 
   bool IsURLAttribute(const Attribute&) const final;

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

@@ -70,13 +70,13 @@ class DataListIndicatorElement final : public HTMLDivElement {
     return new LayoutDetailsMarker(this);
   }
 
-  EventDispatchHandlingState* PreDispatchEventHandler(Event* event) override {
+  EventDispatchHandlingState* PreDispatchEventHandler(Event& event) override {
     // Chromium opens autofill popup in a mousedown event listener
     // associated to the document. We don't want to open it in this case
     // because we opens a datalist chooser later.
     // FIXME: We should dispatch mousedown events even in such case.
-    if (event->type() == EventTypeNames::mousedown)
-      event->stopPropagation();
+    if (event.type() == EventTypeNames::mousedown)
+      event.stopPropagation();
     return nullptr;
   }