Add Keyboard Latency UMA Metrics.

ui/latency/latency_tracker.cc

Index: ui/latency/latency_tracker.cc
diff --git a/ui/latency/latency_tracker.cc b/ui/latency/latency_tracker.cc
index 06701f05d48a8cd2947722f2bb5001a93213d4d4..13f531590515be56f982b056c7b1f17ca9cab65e 100644
--- a/ui/latency/latency_tracker.cc
+++ b/ui/latency/latency_tracker.cc
@@ -18,6 +18,8 @@ std::string LatencySourceEventTypeToInputModalityString(
       return "Wheel";
     case ui::SourceEventType::TOUCH:
       return "Touch";
+    case ui::SourceEventType::KEY:
+      return "Key";
     default:
       return "";
   }
@@ -92,9 +94,10 @@ void LatencyTracker::OnGpuSwapBuffersCompleted(const LatencyInfo& latency) {
 
   ui::SourceEventType source_event_type = latency.source_event_type();
   if (source_event_type == ui::SourceEventType::WHEEL ||
-      source_event_type == ui::SourceEventType::TOUCH) {
-    ComputeTouchAndWheelScrollLatencyHistograms(
-        gpu_swap_begin_component, gpu_swap_end_component, latency);
+      source_event_type == ui::SourceEventType::TOUCH ||
+      source_event_type == ui::SourceEventType::KEY) {
+    ComputeEndToEndLatencyHistograms(gpu_swap_begin_component,
+                                     gpu_swap_end_component, latency);
   }
 
   // Compute the old scroll update latency metrics. They are exclusively
@@ -114,7 +117,7 @@ void LatencyTracker::ReportRapporScrollLatency(
     const LatencyInfo::LatencyComponent& start_component,
     const LatencyInfo::LatencyComponent& end_component) {}
 
-void LatencyTracker::ComputeTouchAndWheelScrollLatencyHistograms(
+void LatencyTracker::ComputeEndToEndLatencyHistograms(
     const ui::LatencyInfo::LatencyComponent& gpu_swap_begin_component,
     const ui::LatencyInfo::LatencyComponent& gpu_swap_end_component,
     const ui::LatencyInfo& latency) {
@@ -165,6 +168,13 @@ void LatencyTracker::ComputeTouchAndWheelScrollLatencyHistograms(
           "Event.Latency.ScrollUpdate.Touch.TimeToScrollUpdateSwapBegin2",
           original_component, gpu_swap_begin_component);
     }
+  } else if (latency.FindLatency(ui::INPUT_EVENT_LATENCY_ORIGINAL_COMPONENT, 0,
+                                 &original_component)) {
+    if (input_modality == "Key") {
+      UMA_HISTOGRAM_INPUT_LATENCY_HIGH_RESOLUTION_MICROSECONDS(
+          "Event.Latency.EndToEnd.Key", original_component,
+          gpu_swap_begin_component);
+    }
   } else {
     // No original component found.
     return;