Move touch slop suppression from LegacyTouchEventQueue to TouchEventManager

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 8d161e1ef2727d4b4eb29e42defb9eefbf560174..165b255623a1b97501e1d09320796dbd6511b5c0 100644
--- a/third_party/WebKit/Source/core/input/TouchEventManager.cpp
+++ b/third_party/WebKit/Source/core/input/TouchEventManager.cpp
@@ -62,6 +62,18 @@ enum TouchEventDispatchResultType {
   TouchEventDispatchResultTypeMax,
 };
 
+bool IsTouchSequenceStart(const PlatformTouchEvent& event) {
+  if (!event.touchPoints().size())
+    return false;
+  if (event.type() != PlatformEvent::TouchStart)
+    return false;
+  for (const auto& point : event.touchPoints()) {
+    if (point.state() != PlatformTouchPoint::TouchPressed)
+      return false;
+  }
+  return true;
+}
+
 // Defining this class type local to dispatchTouchEvents() and annotating
 // it with STACK_ALLOCATED(), runs into MSVC(VS 2013)'s C4822 warning
 // that the local class doesn't provide a local definition for 'operator new'.
@@ -96,6 +108,7 @@ void TouchEventManager::clear() {
   m_regionForTouchID.clear();
   m_touchPressed = false;
   m_currentEvent = PlatformEvent::NoType;
+  m_suppressingTouchmovesWithinSlop = false;
   m_currentTouchAction = TouchActionAuto;
 }
 
@@ -114,6 +127,23 @@ WebInputEventResult TouchEventManager::dispatchTouchEvents(
   // 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() == PlatformEvent::TouchEnd ||
+      event.type() == PlatformEvent::TouchCancel ||
+      event.touchPoints().size() > 1) {
+    m_suppressingTouchmovesWithinSlop = false;
+  }
+
+  if (m_suppressingTouchmovesWithinSlop &&
+      event.type() == PlatformEvent::TouchMove) {
+    if (!event.causesScrollingIfUncanceled())
+      return WebInputEventResult::HandledSuppressed;
+    m_suppressingTouchmovesWithinSlop = false;
+  }
+
   // Holds the complete set of touches on the screen.
   TouchList* touches = TouchList::create();