Remove PlatformEvent it is no longer used.

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

 /**
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2005, 2006, 2007 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 77 matching lines @@
 KeyboardEvent::KeyboardEvent() : m_location(kDomKeyLocationStandard) {}
 
 KeyboardEvent::KeyboardEvent(const WebKeyboardEvent& key,
                              LocalDOMWindow* domWindow)
     : UIEventWithKeyState(
           eventTypeForKeyboardEventType(key.type()),
           true,
           true,
           domWindow,
           0,
-          static_cast<PlatformEvent::Modifiers>(key.modifiers()),
+          static_cast<WebInputEvent::Modifiers>(key.modifiers()),
           TimeTicks::FromSeconds(key.timeStampSeconds()),
           domWindow
               ? domWindow->getInputDeviceCapabilities()->firesTouchEvents(false)
               : nullptr),
       m_keyEvent(WTF::makeUnique<WebKeyboardEvent>(key)),
       // TODO(crbug.com/482880): Fix this initialization to lazy initialization.
       m_code(Platform::current()->domCodeStringFromEnum(key.domCode)),
       m_key(Platform::current()->domKeyStringFromEnum(key.domKey)),
       m_location(keyLocationCode(key)),
       m_isComposing(hasCurrentComposition(domWindow)) {
   initLocationModifiers(m_location);
 }
 
 KeyboardEvent::KeyboardEvent(const AtomicString& eventType,
                              const KeyboardEventInit& initializer)
     : UIEventWithKeyState(eventType, initializer),
       m_code(initializer.code()),
       m_key(initializer.key()),
       m_location(initializer.location()),
       m_isComposing(initializer.isComposing()) {
   if (initializer.repeat())
-    m_modifiers |= PlatformEvent::IsAutoRepeat;
+    m_modifiers |= WebInputEvent::IsAutoRepeat;
   initLocationModifiers(initializer.location());
 }
 
 KeyboardEvent::~KeyboardEvent() {}
 
 void KeyboardEvent::initKeyboardEvent(ScriptState* scriptState,
                                       const AtomicString& type,
                                       bool canBubble,
                                       bool cancelable,
                                       AbstractView* view,
@@ skipping 58 matching lines @@
 int KeyboardEvent::which() const {
   // Netscape's "which" returns a virtual key code for keydown and keyup, and a
   // character code for keypress.  That's exactly what IE's "keyCode" returns.
   // So they are the same for keyboard events.
   return keyCode();
 }
 
 void KeyboardEvent::initLocationModifiers(unsigned location) {
   switch (location) {
     case KeyboardEvent::kDomKeyLocationNumpad:
-      m_modifiers |= PlatformEvent::IsKeyPad;
+      m_modifiers |= WebInputEvent::IsKeyPad;
       break;
     case KeyboardEvent::kDomKeyLocationLeft:
-      m_modifiers |= PlatformEvent::IsLeft;
+      m_modifiers |= WebInputEvent::IsLeft;
       break;
     case KeyboardEvent::kDomKeyLocationRight:
-      m_modifiers |= PlatformEvent::IsRight;
+      m_modifiers |= WebInputEvent::IsRight;
       break;
   }
 }
 
 DEFINE_TRACE(KeyboardEvent) {
   UIEventWithKeyState::trace(visitor);
 }
 
 }  // namespace blink