Remove PlatformEvent it is no longer used.

third_party/WebKit/Source/core/input/GestureManager.h

 // 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.
 
 #ifndef GestureManager_h
 #define GestureManager_h
 
 #include "core/CoreExport.h"
 #include "core/frame/LocalFrame.h"
 #include "core/layout/HitTestRequest.h"
 #include "core/page/EventWithHitTestResults.h"
-#include "platform/PlatformEvent.h"
 #include "public/platform/WebInputEventResult.h"
 #include "wtf/Optional.h"
+#include "wtf/Time.h"
 
 namespace blink {
 
 class ScrollManager;
 class SelectionController;
 class PointerEventManager;
 class MouseEventManager;
 
 // This class takes care of gestures and delegating the action based on the
 // gesture to the responsible class.
@@ skipping 55 matching lines @@
   bool m_longTapShouldInvokeContextMenu;
 
   const Member<SelectionController> m_selectionController;
 
   WTF::Optional<WTF::TimeTicks> m_lastShowPressTimestamp;
 };
 
 }  // namespace blink
 
 #endif  // GestureManager_h