Touch event flag should control only DOM event firing.

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

Index: third_party/WebKit/Source/core/input/TouchEventManager.cpp
diff --git a/third_party/WebKit/Source/core/input/TouchEventManager.cpp b/third_party/WebKit/Source/core/input/TouchEventManager.cpp
index 6880e9f0182af133bf53c42bcfb2e49bd2efe24d..9b40f0b981a737b314f7da31607050c2ab7fea93 100644
--- a/third_party/WebKit/Source/core/input/TouchEventManager.cpp
+++ b/third_party/WebKit/Source/core/input/TouchEventManager.cpp
@@ -18,6 +18,7 @@
 #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>
@@ -485,6 +486,9 @@ class CurrentEventHolder {
 WebInputEventResult TouchEventManager::handleTouchEvent(
     const PlatformTouchEvent& event,
     HeapVector<TouchInfo>& touchInfos) {
+  if (!RuntimeEnabledFeatures::touchEventAPIEnabled())
+    return WebInputEventResult::HandledSystem;

[mustaq, 2016/11/15 20:33:58]

Please return ::NotHandled.

[sunyunjia, 2016/11/16 16:39:58]

The touch event will still be triggered if we return ::NotHandled

+
   // Track the current event for the scope of this function.
   CurrentEventHolder holder(m_currentEvent, event.type());