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

ui/events/base_event_utils.cc

Index: ui/events/base_event_utils.cc
diff --git a/ui/events/base_event_utils.cc b/ui/events/base_event_utils.cc
index 4da72216b1039a57c4424e04252a977e20f430dc..c8eacb161b95d28604e0aef8df2efb28ba1034b8 100644
--- a/ui/events/base_event_utils.cc
+++ b/ui/events/base_event_utils.cc
@@ -7,6 +7,7 @@
 #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"
@@ -42,5 +43,13 @@ bool IsSystemKeyModifier(int flags) {
          (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