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

ui/base/events/event_utils.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/base/events/event_utils.h"
 
 #include "ui/base/events/event.h"
 
 namespace ui {
 
 namespace {
 int g_custom_event_types = ET_LAST;
 }  // namespace
 
 bool EventCanceledDefaultHandling(const Event& event) {
   return event.phase() == EP_POSTTARGET && event.result() != ER_UNHANDLED;
 }
 
 int RegisterCustomEventType() {
   return ++g_custom_event_types;
 }
 
 base::TimeDelta EventTimeForNow() {
   return base::TimeDelta::FromInternalValue(
       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