Fire pointerup/down events for corresponding mouse events.

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 29a8ac7ed8ef95ab40275af2be91d00086052b20..e583c612d15d1a95571507db831a2fa8f99c9069 100644
--- a/third_party/WebKit/Source/core/input/EventHandler.cpp
+++ b/third_party/WebKit/Source/core/input/EventHandler.cpp
@@ -315,6 +315,7 @@ void EventHandler::clear()
     m_scrollbarHandlingScrollGesture = nullptr;
     m_touchPressed = false;
     m_pointerIdManager.clear();
+    m_preventMouseEventForPointerTypeMouse = false;
     m_inPointerCanceledState = false;
     m_mouseDownMayStartDrag = false;
     m_lastShowPressTimestamp = 0;
@@ -969,7 +970,13 @@ bool EventHandler::handleMousePressEvent(const PlatformMouseEvent& mouseEvent)
 
     m_frame->selection().setCaretBlinkingSuspended(true);
 
-    bool swallowEvent = !dispatchMouseEvent(EventTypeNames::mousedown, mev.innerNode(), m_clickCount, mouseEvent);
+    bool swallowEvent = dispatchPointerEventForMouseEvent(mev.innerNode(), EventTypeNames::pointerdown, mouseEvent);
+    if (swallowEvent) {
+        m_preventMouseEventForPointerTypeMouse = true;
+    }
+    if (!m_preventMouseEventForPointerTypeMouse)
+        swallowEvent = swallowEvent || !dispatchMouseEvent(EventTypeNames::mousedown, mev.innerNode(), m_clickCount, mouseEvent);
+
     // m_selectionInitiationState is initialized after dispatching mousedown
     // event in order not to keep the selection by DOM APIs Because we can't
     // give the user the chance to handle the selection by user action like
@@ -1253,7 +1260,10 @@ bool EventHandler::handleMouseReleaseEvent(const PlatformMouseEvent& mouseEvent)
     if (subframe && passMouseReleaseEventToSubframe(mev, subframe))
         return true;
 
-    bool swallowMouseUpEvent = !dispatchMouseEvent(EventTypeNames::mouseup, mev.innerNode(), m_clickCount, mouseEvent);
+    bool swallowPointerUpEvent = dispatchPointerEventForMouseEvent(mev.innerNode(), EventTypeNames::pointerup, mouseEvent);
+    bool swallowMouseUpEvent = false;

[Rick Byers, 2015/10/20 19:09:50]

I think there can be cases where blink doesn't directly see this mouseup (which
you probably need tests for).  Eg:
1. mousedown inside one frame, drag out to parent frame and mouseup there (your
state is per-frame, right?)
2. mousedown inside the window, drag out of the window and mouseup there.  This
will be a little trickier - we don't reliably get MouseLeave notifications from
chromium ATM (Lan is working on this).  Perhaps you just want to reset when you
see any mouse event that has no buttons down?

[mustaq, 2015/10/21 15:17:21]

Yes, this is dependent on Lan's work. Filed crbug/545647 to track this, added a
TODO for now.

I think a reasonable fix would need some mousemove cleanup. Firing pointercancel
on mouse exit could be an intermediate fix but that would still need some
mousemove fix.

Relying on no-button mouseevents sounds scary to me, like our redundant
mousemove bugs.

[mustaq, 2015/10/22 16:42:52]

Here is a patch that resets the "prevent-ME" state upon seeing a no-button
native event as you suggested above.

[Rick Byers, 2015/10/22 21:31:51]

I played with edge a bit here.  To match their behavior I think something like
this is necessary (even if we were getting reliable MouseLeave notifications). 
Note the difference between dragging (with the mouse down) out of a window and
back in, and dragging out, then lifting and moving back in.  The later
definitely cleared the "PREVENT MOUSE EVENT flag" even though no pointerup or
pointercancel was dispatched.  This is perhaps a bug in the spec, do you want to
file one and see what the Edge folks say?  I suspect they'll suggest adding
specific wording around clearing the flag on any event with button=0.

+    if (!m_preventMouseEventForPointerTypeMouse)
+        swallowMouseUpEvent = !dispatchMouseEvent(EventTypeNames::mouseup, mev.innerNode(), m_clickCount, mouseEvent);
 
     bool contextMenuEvent = mouseEvent.button() == RightButton;
 #if OS(MACOSX)
@@ -1280,12 +1290,13 @@ bool EventHandler::handleMouseReleaseEvent(const PlatformMouseEvent& mouseEvent)
     }
 
     bool swallowMouseReleaseEvent = false;
-    if (!swallowMouseUpEvent)
+    if (!swallowPointerUpEvent && !swallowMouseUpEvent)
         swallowMouseReleaseEvent = handleMouseReleaseEvent(mev);
 
     invalidateClick();
 
-    return swallowMouseUpEvent || swallowClickEvent || swallowMouseReleaseEvent;
+    m_preventMouseEventForPointerTypeMouse = false;
+    return swallowPointerUpEvent || swallowMouseUpEvent || swallowClickEvent || swallowMouseReleaseEvent;
 }
 
 bool EventHandler::dispatchDragEvent(const AtomicString& eventType, Node* dragTarget, const PlatformMouseEvent& event, DataTransfer* dataTransfer)