Makes touch event have a time from android

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

Index: mojo/services/input_events/public/interfaces/input_events.mojom
diff --git a/mojo/services/input_events/public/interfaces/input_events.mojom b/mojo/services/input_events/public/interfaces/input_events.mojom
index 008626572d0efd09cb1db132d5128aa7f3c5c9f6..9fa363034e94c4eb99ee19b8a59ce6af6b312106 100644
--- a/mojo/services/input_events/public/interfaces/input_events.mojom
+++ b/mojo/services/input_events/public/interfaces/input_events.mojom
@@ -70,6 +70,8 @@ struct Event {
   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;