Change ui::Event::time_stamp from TimeDelta to TimeTicks

ui/events/base_event_utils.cc

 // 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.
 
 #include "ui/events/base_event_utils.h"
 
 #include "base/atomic_sequence_num.h"
 #include "base/command_line.h"
 #include "base/logging.h"
+#include "base/time/time.h"
 #include "build/build_config.h"
 #include "ui/events/event_constants.h"
 #include "ui/events/event_switches.h"
 
 namespace ui {
 
 namespace {
 
 #if defined(OS_CHROMEOS)
 const int kSystemKeyModifierMask = EF_ALT_DOWN | EF_COMMAND_DOWN;
@@ skipping 15 matching lines @@
   return id;
 }
 
 bool IsSystemKeyModifier(int flags) {
   // AltGr modifier is used to type alternative keys on certain keyboard layouts
   // so we don't consider keys with the AltGr modifier as a system key.
   return (kSystemKeyModifierMask & flags) != 0 &&
          (EF_ALTGR_DOWN & flags) == 0;
 }
 
+double EventTimeStampToSeconds(base::TimeTicks time_stamp) {
+  return (time_stamp - base::TimeTicks()).InSecondsF();
+}
+
+base::TimeTicks EventTimeStampFromSeconds(double time_stamp_seconds) {
+  return base::TimeTicks() + base::TimeDelta::FromSecondsD(time_stamp_seconds);
+}
+
 }  // namespace ui