Makes KeyEvent struct traits restore Event::time_stamp() field

ui/events/event.h

 // Copyright (c) 2012 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_EVENT_H_
 #define UI_EVENTS_EVENT_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 799 matching lines @@
   // be either a keystroke message (WM_KEYUP/WM_KEYDOWN) or a character message
   // (WM_CHAR). Other systems have only keystroke events.
   explicit KeyEvent(const base::NativeEvent& native_event);
 
   // Create a KeyEvent from a NativeEvent but with mocked flags.
   // This method is necessary for Windows since MSG does not contain all flags.
   KeyEvent(const base::NativeEvent& native_event, int event_flags);
 
   // Create a keystroke event from a legacy KeyboardCode.
   // This should not be used in new code.
-  KeyEvent(EventType type, KeyboardCode key_code, int flags);
+  KeyEvent(EventType type,
+           KeyboardCode key_code,
+           int flags,
+           base::TimeTicks time_stamp = base::TimeTicks());
 
   // Create a fully defined keystroke event.
   KeyEvent(EventType type,
            KeyboardCode key_code,
            DomCode code,
            int flags,
            DomKey key,
            base::TimeTicks time_stamp);
 
   // Create a character event.
-  KeyEvent(base::char16 character, KeyboardCode key_code, int flags);
+  KeyEvent(base::char16 character,
+           KeyboardCode key_code,
+           int flags,
+           base::TimeTicks time_stamp = base::TimeTicks());
 
   // Used for synthetic events with code of DOM KeyboardEvent (e.g. 'KeyA')
   // See also: ui/events/keycodes/dom/dom_values.txt
   KeyEvent(EventType type,
            KeyboardCode key_code,
            DomCode code,
            int flags);
 
   KeyEvent(const KeyEvent& rhs);
 
@@ skipping 194 matching lines @@
   // dispatched. This field gets a non-zero value only for gestures that are
   // released through TouchDispositionGestureFilter::SendGesture. The gesture
   // events that aren't fired directly in response to processing a touch-event
   // (e.g. timer fired ones), this id is zero. See crbug.com/618738.
   uint32_t unique_touch_event_id_;
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_EVENT_H_