Touchmoves should not be suppressed if the touchstart is consumed

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/events/TouchEvent.h"
 #include "core/frame/Deprecation.h"
 #include "core/frame/EventHandlerRegistry.h"
@@ skipping 108 matching lines @@
 
 WebInputEventResult TouchEventManager::dispatchTouchEvents(
     const WebTouchEvent& event,
     const HeapVector<TouchInfo>& touchInfos,
     bool allTouchesReleased) {
   // Build up the lists to use for the |touches|, |targetTouches| and
   // |changedTouches| attributes in the JS event. See
   // http://www.w3.org/TR/touch-events/#touchevent-interface for how these
   // lists fit together.
 
-  // Suppress all the touch moves in the slop region.
-  if (IsTouchSequenceStart(event))
-    m_suppressingTouchmovesWithinSlop = true;
-
   if (event.type() == WebInputEvent::TouchEnd ||
       event.type() == WebInputEvent::TouchCancel || event.touchesLength > 1) {
     m_suppressingTouchmovesWithinSlop = false;
   }
 
   if (m_suppressingTouchmovesWithinSlop &&
       event.type() == WebInputEvent::TouchMove) {
     if (!event.movedBeyondSlopRegion)
       return WebInputEventResult::HandledSuppressed;
     m_suppressingTouchmovesWithinSlop = false;
@@ skipping 142 matching lines @@
                   ? HandledTouches
                   : UnhandledTouches);
         }
       }
       eventResult = EventHandlingUtil::mergeEventResult(
           eventResult,
           EventHandlingUtil::toWebInputEventResult(domDispatchResult));
     }
   }
 
+  // Do not suppress any touchmoves if the touchstart is consumed.
+  if (IsTouchSequenceStart(event) &&
+      eventResult == WebInputEventResult::NotHandled) {
+    m_suppressingTouchmovesWithinSlop = true;
+  }
+
   return eventResult;
 }
 
 void TouchEventManager::updateTargetAndRegionMapsForTouchStarts(
     HeapVector<TouchInfo>& touchInfos) {
   for (auto& touchInfo : touchInfos) {
     // Touch events implicitly capture to the touched node, and don't change
     // active/hover states themselves (Gesture events do). So we only need
     // to hit-test on touchstart and when the target could be different than
     // the corresponding pointer event target.
@@ skipping 207 matching lines @@
   }
 
   return dispatchTouchEvents(event, touchInfos, allTouchesReleased);
 }
 
 bool TouchEventManager::isAnyTouchActive() const {
   return m_touchPressed;
 }
 
 }  // namespace blink