Add UMA metric for tracking root level listeners for blocking touch.

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 257 matching lines @@
     , m_mousePositionIsUnknown(true)
     , m_mouseDownTimestamp(0)
     , m_touchPressed(false)
     , m_inPointerCanceledState(false)
     , m_scrollGestureHandlingNode(nullptr)
     , m_lastGestureScrollOverWidget(false)
     , m_longTapShouldInvokeContextMenu(false)
     , m_activeIntervalTimer(this, &EventHandler::activeIntervalTimerFired)
     , m_lastShowPressTimestamp(0)
     , m_deltaConsumedForScrollSequence(false)
+    , m_waitingForFirstTouchMove(false)
 {
 }
 
 EventHandler::~EventHandler()
 {
     ASSERT(!m_fakeMouseMoveEventTimer.isActive());
 }
 
 DEFINE_TRACE(EventHandler)
 {
@@ skipping 3359 matching lines @@
     using EventTargetSet = HeapHashSet<Member<EventTarget>>;
     // Set of targets involved in m_touches.
     EventTargetSet m_targets;
 };
 
 } // namespace
 
 WebInputEventResult EventHandler::dispatchTouchEvents(const PlatformTouchEvent& event,
     HeapVector<TouchInfo>& touchInfos, bool freshTouchEvents, bool allTouchReleased)
 {
+    bool firstTouchMoveAfterTouchStart = false;
+    if (event.type() == PlatformEvent::TouchStart) {
+        m_waitingForFirstTouchMove = true;
+    } else if (event.type() == PlatformEvent::TouchMove) {
+        firstTouchMoveAfterTouchStart = m_waitingForFirstTouchMove;
+        m_waitingForFirstTouchMove = false;
+    }
+
     // Build up the lists to use for the 'touches', 'targetTouches' and
     // 'changedTouches' attributes in the JS event. See
     // http://www.w3.org/TR/touch-events/#touchevent-interface for how these
     // lists fit together.
 
     // Holds the complete set of touches on the screen.
     RawPtr<TouchList> touches = TouchList::create();
 
     // A different view on the 'touches' list above, filtered and grouped by
     // event target. Used for the 'targetTouches' list in the JS event.
@@ skipping 64 matching lines @@
     for (unsigned state = 0; state != PlatformTouchPoint::TouchStateEnd; ++state) {
         if (!changedTouches[state].m_touches)
             continue;
 
         const AtomicString& eventName(touchEventNameForTouchPointState(static_cast<PlatformTouchPoint::TouchState>(state)));
         for (const auto& eventTarget : changedTouches[state].m_targets) {
             EventTarget* touchEventTarget = eventTarget.get();
             RawPtr<TouchEvent> touchEvent = TouchEvent::create(
                 touches.get(), touchesByTarget.get(touchEventTarget), changedTouches[state].m_touches.get(),
                 eventName, touchEventTarget->toNode()->document().domWindow(),
-                event.getModifiers(), event.cancelable(), event.causesScrollingIfUncanceled(), event.timestamp());
+                event.getModifiers(), event.cancelable(), event.causesScrollingIfUncanceled(), firstTouchMoveAfterTouchStart, event.timestamp());
 
             eventResult = mergeEventResult(eventResult, toWebInputEventResult(touchEventTarget->dispatchEvent(touchEvent.get())));
         }
     }
 
     return eventResult;
 }
 
 WebInputEventResult EventHandler::handleTouchEvent(const PlatformTouchEvent& event)
 {
@@ skipping 254 matching lines @@
 PlatformEvent::Modifiers EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return static_cast<PlatformEvent::Modifiers>(PlatformEvent::CtrlKey | PlatformEvent::AltKey);
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace blink