Add UMA metrics for measuring number of coalesed events and their latency.

ui/base/events/event_utils.cc

Index: ui/base/events/event_utils.cc
diff --git a/ui/base/events/event_utils.cc b/ui/base/events/event_utils.cc
index ac09854bbfb9319dc46ec2a018b1444212677993..e530cff904dbd1cff0d4c15eed2fb582bc1ec7e0 100644
--- a/ui/base/events/event_utils.cc
+++ b/ui/base/events/event_utils.cc
@@ -25,4 +25,30 @@ base::TimeDelta EventTimeForNow() {
       base::TimeTicks::Now().ToInternalValue());
 }
 
+bool IsKeyEventType(EventType type) {
+  return type == ET_KEY_PRESSED ||
+         type == ET_KEY_RELEASED ||
+         type == ET_TRANSLATED_KEY_PRESS ||
+         type == ET_TRANSLATED_KEY_RELEASE;
+}
+
+bool IsMouseEventType(EventType type) {
+  return type == ET_MOUSE_PRESSED ||
+         type == ET_MOUSE_DRAGGED ||
+         type == ET_MOUSE_RELEASED ||
+         type == ET_MOUSE_MOVED ||
+         type == ET_MOUSE_ENTERED ||
+         type == ET_MOUSE_EXITED ||
+         type == ET_MOUSEWHEEL ||
+         type == ET_MOUSE_CAPTURE_CHANGED;
+}
+
+bool IsTouchEventType(EventType type) {
+  return type == ET_TOUCH_RELEASED ||
+         type == ET_TOUCH_PRESSED ||
+         type == ET_TOUCH_MOVED ||
+         type == ET_TOUCH_STATIONARY ||
+         type == ET_TOUCH_CANCELLED;
+}
+
 }  // namespace ui