Don't log a console warning when touch-action is used.

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 @@
   return false;
 }
 
 void Event::preventDefault() {
   if (m_handlingPassive != PassiveMode::NotPassive &&
       m_handlingPassive != PassiveMode::NotPassiveDefault) {
     m_preventDefaultCalledDuringPassive = true;
 
     const LocalDOMWindow* window =
         m_eventPath ? m_eventPath->windowEventContext().window() : 0;
-    if (window) {
+    if (window && shouldLogPassiveDevtoolsWarning()) {
       const char* devToolsMsg = nullptr;
       switch (m_handlingPassive) {
         case PassiveMode::NotPassive:
         case PassiveMode::NotPassiveDefault:
           NOTREACHED();
           break;
         case PassiveMode::Passive:
         case PassiveMode::PassiveDefault:
           devToolsMsg =
               "Unable to preventDefault inside passive event listener "
               "invocation.";
           break;
         case PassiveMode::PassiveForcedDocumentLevel:

[Rick Byers, 2016/11/22 20:40:33]

I think this would get a little cleaner (and avoid the need to add another
virtual on Event) if you moved this case into TouchEvent::preventDefault.  I.e.
keep the touch-intervention-specific stuff to TouchEvent as much as possible. 
There's already a bunch of related code in TouchEvent::preventDefault.  WDYT?

           devToolsMsg =
               "Unable to preventDefault inside passive event listener due to "
               "target being treated as passive. See "
               "https://www.chromestatus.com/features/5093566007214080";
           break;
       }
       if (devToolsMsg)
         window->printErrorMessage(devToolsMsg);
     }
     return;
@@ skipping 115 matching lines @@
 }
 
 DEFINE_TRACE(Event) {
   visitor->trace(m_currentTarget);
   visitor->trace(m_target);
   visitor->trace(m_underlyingEvent);
   visitor->trace(m_eventPath);
 }
 
 }  // namespace blink