Record accuracy of expected queueing time metric.

ui/latency/latency_info.h

Index: ui/latency/latency_info.h
diff --git a/ui/latency/latency_info.h b/ui/latency/latency_info.h
index 2dcf550ec3823b3519275847d26b477f7c050886..218dce92fdb0de81ddbbdc84b26b45c809511b0c 100644
--- a/ui/latency/latency_info.h
+++ b/ui/latency/latency_info.h
@@ -208,6 +208,15 @@ class LatencyInfo {
     source_event_type_ = type;
   }
 
+  void set_expected_queueing_time_on_dispatch(
+      base::TimeDelta expected_queueing_time) {
+    expected_queueing_time_on_dispatch_ = expected_queueing_time;
+  }
+
+  base::TimeDelta expected_queueing_time_on_dispatch() const {
+    return expected_queueing_time_on_dispatch_;
+  }
+
   bool began() const { return began_; }
   bool terminated() const { return terminated_; }
   void set_coalesced() { coalesced_ = true; }
@@ -243,6 +252,9 @@ class LatencyInfo {
   bool terminated_;
   // Stores the type of the first source event.
   SourceEventType source_event_type_;
+  // The expected queueing time on the main thread when this event was
+  // dispatched.
+  base::TimeDelta expected_queueing_time_on_dispatch_;
 
 #if !defined(OS_IOS)
   friend struct IPC::ParamTraits<ui::LatencyInfo>;