Non passive touch end or touch cancel listeners should not block scroll.

third_party/WebKit/Source/core/frame/EventHandlerRegistry.h

 // Copyright 2014 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.
 
 #ifndef EventHandlerRegistry_h
 #define EventHandlerRegistry_h
 
 #include "core/CoreExport.h"
 #include "core/frame/FrameHost.h"
 #include "wtf/HashCountedSet.h"
@@ skipping 14 matching lines @@
     explicit EventHandlerRegistry(FrameHost&);
     virtual ~EventHandlerRegistry();
 
     // Supported event handler classes. Note that each one may correspond to
     // multiple event types.
     enum EventHandlerClass {
         ScrollEvent,
         WheelEventBlocking,
         WheelEventPassive,
         TouchEventBlocking,
         TouchEventPassive,

[Rick Byers, 2016/04/14 01:41:41]

Please rename these to TouchStartOrMove* for symmetry and to avoid confusion.

[dtapuska, 2016/04/14 01:49:10]

Do you want the WebEventListenerClass enum renamed too?

[dtapuska, 2016/04/14 14:41:11]

Done.

+        TouchEndOrCancelEventBlocking,
+        TouchEndOrCancelEventPassive,
 #if ENABLE(ASSERT)
         // Additional event categories for verifying handler tracking logic.
         EventsForTesting,
 #endif
         EventHandlerClassCount, // Must be the last entry.
     };
 
     // Returns true if the FrameHost has event handlers of the specified class.
     bool hasEventHandlers(EventHandlerClass) const;
 
@@ skipping 27 matching lines @@
         RemoveAll // Remove any and all existing event handlers for a given target.
     };
 
     // Returns true if |eventType| belongs to a class this registry tracks.
     static bool eventTypeToClass(const AtomicString& eventType, const EventListenerOptions&, EventHandlerClass* result);
 
     // Returns true if the operation actually added a new target or completely
     // removed an existing one.
     bool updateEventHandlerTargets(ChangeOperation, EventHandlerClass, EventTarget*);
 
+    // Update whether we have any touch handler or not.
+    void updateHasTouchEventListeners();
+
     // Called on the EventHandlerRegistry of the root Document to notify
     // clients when we have added the first handler or removed the last one for
     // a given event class. |hasActiveHandlers| can be used to distinguish
     // between the two cases.
     void notifyHasHandlersChanged(EventHandlerClass, bool hasActiveHandlers);
 
     // Called to notify clients whenever a single event handler target is
     // registered or unregistered. If several handlers are registered for the
     // same target, only the first registration will trigger this notification.
     void notifyDidAddOrRemoveEventHandlerTarget(EventHandlerClass);
 
     // Record a change operation to a given event handler class and notify any
     // parent registry and other clients accordingly.
     void updateEventHandlerOfType(ChangeOperation, const AtomicString& eventType, const EventListenerOptions&, EventTarget*);
 
     void updateEventHandlerInternal(ChangeOperation, EventHandlerClass, EventTarget*);
 
     void updateAllEventHandlers(ChangeOperation, EventTarget&);
 
     void checkConsistency() const;
 
     Member<FrameHost> m_frameHost;
     EventTargetSet m_targets[EventHandlerClassCount];
 };
 
 } // namespace blink
 
 #endif // EventHandlerRegistry_h