Remove PlatformEvent it is no longer used.

third_party/WebKit/Source/core/events/PointerEventFactory.cpp

 // Copyright 2016 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/events/PointerEventFactory.h"
 
 #include "core/frame/FrameView.h"
 #include "platform/geometry/FloatSize.h"
 
 namespace blink {
@@ skipping 207 matching lines @@
     const WebMouseEvent& mouseEvent,
     const Vector<WebMouseEvent>& coalescedMouseEvents,
     LocalDOMWindow* view) {
   DCHECK(mouseEventName == EventTypeNames::mousemove ||
          mouseEventName == EventTypeNames::mousedown ||
          mouseEventName == EventTypeNames::mouseup);
 
   AtomicString pointerEventName =
       pointerEventNameForMouseEventName(mouseEventName);
 
-  unsigned buttons = MouseEvent::platformModifiersToButtons(
-      static_cast<PlatformEvent::Modifiers>(mouseEvent.modifiers()));
+  unsigned buttons = MouseEvent::webInputEventModifiersToButtons(
+      static_cast<WebInputEvent::Modifiers>(mouseEvent.modifiers()));
   PointerEventInit pointerEventInit;
 
   setIdTypeButtons(pointerEventInit, mouseEvent, buttons);
   setEventSpecificFields(pointerEventInit, pointerEventName);
 
   if (pointerEventName == EventTypeNames::pointerdown ||
       pointerEventName == EventTypeNames::pointerup) {
     WebPointerProperties::Button button = mouseEvent.button;
     // TODO(mustaq): Fix when the spec starts supporting hovering erasers.
     if (mouseEvent.pointerType == WebPointerProperties::PointerType::Eraser &&
@@ skipping 277 matching lines @@
     const WebPointerProperties& properties) const {
   if (properties.pointerType == WebPointerProperties::PointerType::Mouse)
     return PointerEventFactory::s_mouseId;
   IncomingId id(properties.pointerType, properties.id);
   if (m_pointerIncomingIdMapping.contains(id))
     return m_pointerIncomingIdMapping.get(id);
   return PointerEventFactory::s_invalidId;
 }
 
 }  // namespace blink