WIP: Plumbing input event latency reporting through Mus GPU.

ui/events/mojo/latency_info.mojom

Index: ui/events/mojo/latency_info.mojom
diff --git a/ui/events/mojo/latency_info.mojom b/ui/events/mojo/latency_info.mojom
index e5e77de3b77d28caacaa84a2398ee03c78811cfe..072047fee744451b0d4709ea4ab1bdc0d1356809 100644
--- a/ui/events/mojo/latency_info.mojom
+++ b/ui/events/mojo/latency_info.mojom
@@ -89,6 +89,13 @@ struct LatencyComponent {
   mojo.common.mojom.TimeTicks event_time;
   // Count of events that happened in this component
   uint32 event_count;
+  // TODO(mfomitchev): Do we really need these? We are shipping these cross-IPC
+  // with every frame and for every event for every component. Seems like a lot of
+  // waste
+   // Time of the oldest event that happened in this component.
+  mojo.common.mojom.TimeTicks first_event_time;
+  // Time of the most recent event that happened in this component.
+  mojo.common.mojom.TimeTicks last_event_time;
 };
 
 struct LatencyComponentPair {