Makes touch event have a time from android

mojo/services/input_events/public/interfaces/input_events.mojom

 // Copyright 2014 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.
 
 module mojo;
 
 import "geometry/public/interfaces/geometry.mojom";
 import "input_events/public/interfaces/input_event_constants.mojom";
 import "input_events/public/interfaces/input_key_codes.mojom";
 
@@ skipping 52 matching lines @@
   // Used for devices that support wheels. Ranges from -1 to 1.
   float horizontal_wheel;
   float vertical_wheel;
 };
 
 struct Event {
   // TODO(sky): rename to type.
   EventType action;
   // TODO(sky): parts of this should move to PointerData.
   EventFlags flags;
+  // Time the event was delivered. The time is in milliseconds and corresponds
+  // to the uptime of the machine.
   int64 time_stamp;
   KeyData? key_data;
   PointerData? pointer_data;
 };