Validate that ui::Event::time_stamp comes from the same clock as TimeTicks::Now

ui/events/x/events_x.cc

 // 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.
 
 #include "ui/events/event_utils.h"
 
 #include <stddef.h>
 #include <string.h>
 #include <X11/extensions/XInput.h>
 #include <X11/extensions/XInput2.h>
@@ skipping 67 matching lines @@
 
 EventType EventTypeFromNative(const base::NativeEvent& native_event) {
   return EventTypeFromXEvent(*native_event);
 }
 
 int EventFlagsFromNative(const base::NativeEvent& native_event) {
   return EventFlagsFromXEvent(*native_event);
 }
 
 base::TimeTicks EventTimeFromNative(const base::NativeEvent& native_event) {
-  return EventTimeFromXEvent(*native_event);
+  base::TimeTicks timestamp = EventTimeFromXEvent(*native_event);
+  ValidateEventTimeClock(&timestamp);
+  return timestamp;
 }
 
 gfx::Point EventLocationFromNative(const base::NativeEvent& native_event) {
   return EventLocationFromXEvent(*native_event);
 }
 
 gfx::Point EventSystemLocationFromNative(
     const base::NativeEvent& native_event) {
   return EventSystemLocationFromXEvent(*native_event);
 }
@@ skipping 126 matching lines @@
       xievent->detail =
           UpdateX11EventButton(event->changed_button_flags(), xievent->detail);
       break;
     }
     default:
       break;
   }
 }
 
 }  // namespace ui