ui: Cleanup class/struct forward declarations

ui/events/blink/blink_event_util.h

 // Copyright 2015 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 UI_EVENTS_BLINK_BLINK_EVENT_UTIL_H_
 #define UI_EVENTS_BLINK_BLINK_EVENT_UTIL_H_
 
 #include <memory>
 
 #include "third_party/WebKit/public/platform/WebInputEvent.h"
 #include "ui/events/gesture_detection/motion_event.h"
 
-namespace base {
-class TimeDelta;
-}
-
 namespace blink {
 class WebGestureEvent;
 class WebInputEvent;
 class WebTouchEvent;
 }
 
 namespace gfx {
 class PointF;
 class Vector2d;
 }
@@ skipping 39 matching lines @@
     MotionEvent::ToolType tool_type);
 
 int WebEventModifiersToEventFlags(int modifiers);
 
 blink::WebInputEvent::Modifiers DomCodeToWebInputEventModifiers(
     ui::DomCode code);
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_BLINK_BLINK_EVENT_UTIL_H_