Touch event flag should control only DOM event firing.

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

 // Copyright 2016 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 "core/input/TouchEventManager.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/DocumentUserGestureToken.h"
 #include "core/events/TouchEvent.h"
 #include "core/frame/Deprecation.h"
 #include "core/frame/EventHandlerRegistry.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
 #include "core/html/HTMLCanvasElement.h"
 #include "core/input/EventHandlingUtil.h"
 #include "core/input/TouchActionUtil.h"
 #include "core/layout/HitTestCanvasResult.h"
 #include "core/page/ChromeClient.h"
 #include "core/page/Page.h"
 #include "platform/Histogram.h"
 #include "platform/PlatformTouchEvent.h"
+#include "platform/RuntimeEnabledFeatures.h"
 #include "wtf/CurrentTime.h"
 #include "wtf/PtrUtil.h"
 #include <memory>
 
 namespace blink {
 
 namespace {
 
 bool hasTouchHandlers(const EventHandlerRegistry& registry) {
   return registry.hasEventHandlers(
@@ skipping 448 matching lines @@
   }
   ~CurrentEventHolder() { m_target = PlatformEvent::NoType; }
 
  private:
   PlatformEvent::EventType& m_target;
 };
 
 WebInputEventResult TouchEventManager::handleTouchEvent(
     const PlatformTouchEvent& event,
     HeapVector<TouchInfo>& touchInfos) {
+  if (!RuntimeEnabledFeatures::touchAPIEnabled())
+    return WebInputEventResult::HandledSystem;

[mustaq, 2016/11/03 18:10:49]

Should be NotHandled instead, to let the upstream event handlers know that the
page didn't do anything with the event. Could be HandledSuppressed, depends on
how the return value is used.

+
   // Track the current event for the scope of this function.
   CurrentEventHolder holder(m_currentEvent, event.type());
 
   if (!reHitTestTouchPointsIfNeeded(event, touchInfos))
     return WebInputEventResult::NotHandled;
 
   bool allTouchesReleased = true;
   for (const auto& point : event.touchPoints()) {
     if (point.state() != PlatformTouchPoint::TouchReleased &&
         point.state() != PlatformTouchPoint::TouchCancelled)
@@ skipping 65 matching lines @@
       feature = UseCounter::TouchEndDuringScrollUserGestureUtilized;
       break;
     default:
       NOTREACHED();
       return;
   }
   Deprecation::countDeprecation(m_frame, feature);
 }
 
 }  // namespace blink