PointerEvents for long-press: fix double firing & canceling MEs

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

Index: third_party/WebKit/Source/core/input/EventHandler.cpp
diff --git a/third_party/WebKit/Source/core/input/EventHandler.cpp b/third_party/WebKit/Source/core/input/EventHandler.cpp
index 8c2790eee6eed70c0a7c97cedfb7a49c002fa6dd..3cd4be1230b0e4d121a703afa897e124990dd3bd 100644
--- a/third_party/WebKit/Source/core/input/EventHandler.cpp
+++ b/third_party/WebKit/Source/core/input/EventHandler.cpp
@@ -774,7 +774,7 @@ static LayoutPoint contentPointFromRootFrame(LocalFrame* frame, const IntPoint&
     return view ? view->rootFrameToContents(pointInRootFrame) : pointInRootFrame;
 }
 
-WebInputEventResult EventHandler::handleMousePressEvent(const PlatformMouseEvent& mouseEvent)
+WebInputEventResult EventHandler::handleMousePressEvent(const PlatformMouseEvent& mouseEvent, const bool synthesizedFromTouch)
 {
     TRACE_EVENT0("blink", "EventHandler::handleMousePressEvent");
 
@@ -853,7 +853,8 @@ WebInputEventResult EventHandler::handleMousePressEvent(const PlatformMouseEvent
     if (!mouseEvent.fromTouch())
         m_frame->selection().setCaretBlinkingSuspended(true);
 
-    WebInputEventResult eventResult = updatePointerTargetAndDispatchEvents(EventTypeNames::mousedown, mev.innerNode(), m_clickCount, mev.event());
+    WebInputEventResult eventResult = updatePointerTargetAndDispatchEvents(
+        EventTypeNames::mousedown, mev.innerNode(), m_clickCount, mev.event(), synthesizedFromTouch);
 
     if (eventResult == WebInputEventResult::NotHandled && m_frame->view()) {
         FrameView* view = m_frame->view();
@@ -872,8 +873,9 @@ WebInputEventResult EventHandler::handleMousePressEvent(const PlatformMouseEvent
     // the same behavior and it's more compatible with other browsers.
     selectionController().initializeSelectionState();
     HitTestResult hitTestResult = hitTestResultInFrame(m_frame, documentPoint, HitTestRequest::ReadOnly);
-    InputDeviceCapabilities* sourceCapabilities = mouseEvent.getSyntheticEventType() == PlatformMouseEvent::FromTouch ? InputDeviceCapabilities::firesTouchEventsSourceCapabilities() :
-        InputDeviceCapabilities::doesntFireTouchEventsSourceCapabilities();
+    InputDeviceCapabilities* sourceCapabilities = mouseEvent.getSyntheticEventType() == PlatformMouseEvent::FromTouch
+        ? InputDeviceCapabilities::firesTouchEventsSourceCapabilities()
+        : InputDeviceCapabilities::doesntFireTouchEventsSourceCapabilities();
     if (eventResult == WebInputEventResult::NotHandled)
         eventResult = handleMouseFocus(MouseEventWithHitTestResults(mev.event(), hitTestResult), sourceCapabilities);
     m_capturesDragging = eventResult == WebInputEventResult::NotHandled || mev.scrollbar();
@@ -1497,7 +1499,7 @@ void EventHandler::elementRemoved(EventTarget* target)
 }
 
 // TODO(mustaq): Make PE drive ME dispatch & bookkeeping in EventHandler.
-WebInputEventResult EventHandler::updatePointerTargetAndDispatchEvents(const AtomicString& mouseEventType, Node* targetNode, int clickCount, const PlatformMouseEvent& mouseEvent)
+WebInputEventResult EventHandler::updatePointerTargetAndDispatchEvents(const AtomicString& mouseEventType, Node* targetNode, int clickCount, const PlatformMouseEvent& mouseEvent, const bool synthesizedFromTouch)
 {
     ASSERT(mouseEventType == EventTypeNames::mousedown
         || mouseEventType == EventTypeNames::mousemove
@@ -1505,6 +1507,9 @@ WebInputEventResult EventHandler::updatePointerTargetAndDispatchEvents(const Ato
 
     Node* lastNodeUnderMouse = updateMouseEventTargetNode(targetNode, mouseEvent);
 
+    if (synthesizedFromTouch)
+        return dispatchMouseEvent(mouseEventType, m_nodeUnderMouse, clickCount, mouseEvent);
+
     return m_pointerEventManager.sendMousePointerEvent(
         m_nodeUnderMouse, mouseEventType, clickCount, mouseEvent, nullptr,
         lastNodeUnderMouse);
@@ -2389,7 +2394,9 @@ WebInputEventResult EventHandler::sendContextMenuEventForGesture(const GestureEv
     // To simulate right-click behavior, we send a right mouse down and then
     // context menu event.
     // FIXME: Send HitTestResults to avoid redundant hit tests.
-    handleMousePressEvent(mouseEvent);
+
+    handleMousePressEvent(mouseEvent, true);

[Rick Byers, 2016/07/14 14:27:10]

I think the real bug here related to the above FIXME and TODO comments.  

HandleGestureTap is careful to be explicit about what additional hit-tests need
to happen and call only in to the DOM mouse-event generation logic.  But here
we're calling the raw PlatformMouseEvent entrypoint.  That seems inconsistent
and wrong.  Couldn't we just follow the same pattern as HandleGestureTap (and
for the mousemove above) and invoke just the DOM event-generation logic rather
than re-using the entire low-level handleMousePressEvent code path?

That would then also open up the possibility of not firing the mousedown (I
think we probably shouldn't) and potentially avoiding the hit-test (though it
might be required for web compat).

Is that easy to do without a ton of code duplication / refactoring?  At a
minimum you shouldn't have to add any new "from touch" tracking, you've already
marked the PlatformMouseEvent as "FromTouch" above.

[mustaq, 2016/07/14 15:05:14]

I tried to address the TODO but Edge sends mousedown/up before a contextmenu
event triggerred by a long-tap, so suppressing them looks breaking to me. I will
avoid doing it in this CL.

Also considered triggering only the DOM generation logic here but that would
bypass all the mouse-pressed related bookkeeping we are triggering here for
GestureLongPree, GestureLongTap & GestureTwoFingerTap. Do you it is safe to do
so?

I missed the FromTouch bit here, will use it if minimal DOM event generation
seems unsafe.

+
     return sendContextMenuEvent(mouseEvent);
     // We do not need to send a corresponding mouse release because in case of
     // right-click, the context menu takes capture and consumes all events.