Add UMA metrics for root scroller intervention to track forcing passive breakage.

third_party/WebKit/Source/core/events/Event.cpp

 /*
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2005, 2006, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 207 matching lines @@
 }
 
 bool Event::isBeforeUnloadEvent() const
 {
     return false;
 }
 
 void Event::preventDefault()
 {
     if (m_handlingPassive) {
+        m_preventDefaultCalledDuringPassive = true;
         const LocalDOMWindow* window = m_eventPath ? m_eventPath->windowEventContext().window() : 0;
         if (window)
             window->printErrorMessage("Unable to preventDefault inside passive event listener invocation.");
         return;
     }
 
     if (m_cancelable)
         m_defaultPrevented = true;
 }
 
@@ skipping 32 matching lines @@
 HeapVector<Member<EventTarget>> Event::path(ScriptState* scriptState) const
 {
     return pathInternal(scriptState, NonEmptyAfterDispatch);
 }
 
 HeapVector<Member<EventTarget>> Event::composedPath(ScriptState* scriptState) const
 {
     return pathInternal(scriptState, EmptyAfterDispatch);
 }
 
+void Event::setHandlingPassive(bool value)
+{
+    m_handlingPassive = value;
+    m_preventDefaultCalledDuringPassive = false;
+}
+
 HeapVector<Member<EventTarget>> Event::pathInternal(ScriptState* scriptState, EventPathMode mode) const
 {
     if (m_target)
         HostsUsingFeatures::countHostOrIsolatedWorldHumanReadableName(scriptState, *m_target, HostsUsingFeatures::Feature::EventPath);
 
     if (!m_currentTarget) {
         ASSERT(m_eventPhase == Event::NONE);
         if (!m_eventPath) {
             // Before dispatching the event
             return HeapVector<Member<EventTarget>>();
@@ skipping 70 matching lines @@
 
 DEFINE_TRACE(Event)
 {
     visitor->trace(m_currentTarget);
     visitor->trace(m_target);
     visitor->trace(m_underlyingEvent);
     visitor->trace(m_eventPath);
 }
 
 } // namespace blink