Added UseCounters for touchstart, mousedown, pointerdown invocation

third_party/WebKit/Source/core/input/PointerEventManager.cpp

Index: third_party/WebKit/Source/core/input/PointerEventManager.cpp
diff --git a/third_party/WebKit/Source/core/input/PointerEventManager.cpp b/third_party/WebKit/Source/core/input/PointerEventManager.cpp
index c3cb5b770a9521f9937ea289373426c9127a9dcf..75dd2416a58f27bdc838978e100bf34bde0d733b 100644
--- a/third_party/WebKit/Source/core/input/PointerEventManager.cpp
+++ b/third_party/WebKit/Source/core/input/PointerEventManager.cpp
@@ -156,6 +156,9 @@ WebInputEventResult PointerEventManager::dispatchPointerEvent(
         return WebInputEventResult::NotHandled;
     if (!checkForListener || target->hasEventListeners(eventType)) {
         UseCounter::count(m_frame->document(), UseCounter::PointerEventDispatch);
+        if (eventType == EventTypeNames::pointerdown)
+            UseCounter::count(m_frame->document(), UseCounter::PointerEventDispatchPointerDown);
+
         DispatchEventResult dispatchResult = target->dispatchEvent(pointerEvent);
         return EventHandler::toWebInputEventResult(dispatchResult);
     }