Add Keyboard Latency UMA Metrics.

content/browser/renderer_host/input/render_widget_host_latency_tracker.cc

Index: content/browser/renderer_host/input/render_widget_host_latency_tracker.cc
diff --git a/content/browser/renderer_host/input/render_widget_host_latency_tracker.cc b/content/browser/renderer_host/input/render_widget_host_latency_tracker.cc
index 5ec74f7da9d699e76cc479034c6775d906576abe..a3ed17413621cbb7102874b139094fe157173efe 100644
--- a/content/browser/renderer_host/input/render_widget_host_latency_tracker.cc
+++ b/content/browser/renderer_host/input/render_widget_host_latency_tracker.cc
@@ -103,7 +103,8 @@ void RenderWidgetHostLatencyTracker::ComputeInputLatencyHistograms(
     return;
 
   if (type != blink::WebInputEvent::kMouseWheel &&
-      !WebInputEvent::IsTouchEventType(type)) {
+      !WebInputEvent::IsTouchEventType(type) &&
+      !WebInputEvent::IsKeyboardEventType(type)) {
     return;
   }
 
@@ -127,20 +128,28 @@ void RenderWidgetHostLatencyTracker::ComputeInputLatencyHistograms(
     if (type == blink::WebInputEvent::kMouseWheel) {
       UMA_HISTOGRAM_CUSTOM_COUNTS("Event.Latency.Browser.WheelUI",
                                   ui_delta.InMicroseconds(), 1, 20000, 100);
-    } else {
-      DCHECK(WebInputEvent::IsTouchEventType(type));
+    } else if (WebInputEvent::IsTouchEventType(type)) {
       UMA_HISTOGRAM_CUSTOM_COUNTS("Event.Latency.Browser.TouchUI",
                                   ui_delta.InMicroseconds(), 1, 20000, 100);
+    } else if (WebInputEvent::IsKeyboardEventType(type)) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS("Event.Latency.Browser.KeyUI",
+                                  ui_delta.InMicroseconds(), 1, 20000, 50);
+    } else {
+      // We should only report these histograms for wheel, touch and keyboard.
+      NOTREACHED();
     }
   }
 
-  // Both tap and scroll gestures depend on the disposition of the touch start
-  // and the current touch. For touch start, touch_start_default_prevented_ ==
-  // (ack_result == INPUT_EVENT_ACK_STATE_CONSUMED).
+  // Touchscreen tap and scroll gestures depend on the disposition of the touch
+  // start and the current touch. For touch start,
+  // touch_start_default_prevented_ == (ack_result ==
+  // INPUT_EVENT_ACK_STATE_CONSUMED).
   bool action_prevented = touch_start_default_prevented_ ||
                           ack_result == INPUT_EVENT_ACK_STATE_CONSUMED;
 
   std::string event_name = WebInputEvent::GetName(type);
+  if (WebInputEvent::IsKeyboardEventType(type))
+    event_name = "KeyEvent";
 
   std::string default_action_status =
       action_prevented ? "DefaultPrevented" : "DefaultAllowed";