Remove PlatformEvent it is no longer used.

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

 /*
  * Copyright 2008, The Android Open Source Project
  * Copyright (C) 2012 Research In Motion Limited. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *  * Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *  * Redistributions in binary form must reproduce the above copyright
@@ skipping 199 matching lines @@
                        TouchAction currentTouchAction)
     // Pass a sourceCapabilities including the ability to fire touchevents when
     // creating this touchevent, which is always created from input device
     // capabilities from EventHandler.
     : UIEventWithKeyState(
           type,
           true,
           event.isCancelable(),
           view,
           0,
-          static_cast<PlatformEvent::Modifiers>(event.modifiers()),
+          static_cast<WebInputEvent::Modifiers>(event.modifiers()),
           TimeTicks::FromSeconds(event.timeStampSeconds()),
           view ? view->getInputDeviceCapabilities()->firesTouchEvents(true)
                : nullptr),
       m_touches(touches),
       m_targetTouches(targetTouches),
       m_changedTouches(changedTouches),
       m_defaultPreventedBeforeCurrentTarget(false),
       m_currentTouchAction(currentTouchAction) {
   m_nativeEvent.reset(new WebTouchEvent(event));
 }
@@ skipping 140 matching lines @@
   return toTouchEvent(EventDispatchMediator::event());
 }
 
 DispatchEventResult TouchEventDispatchMediator::dispatchEvent(
     EventDispatcher& dispatcher) const {
   event().eventPath().adjustForTouchEvent(event());
   return dispatcher.dispatch();
 }
 
 }  // namespace blink