Bug 1653949 - Part 2: Add ePuppet to WidgetMouseEvent::ExitFrom; r=smaug

eTopLevel is reused in content process to indicates that the mouse leaves
the puppet widget rendering area, now we add a separated type, ePuppet, for it.

Differential Revision: https://phabricator.services.mozilla.com/D84748

dom/base/nsContentUtils.cpp

@@ -7835,7 +7835,8 @@ nsresult nsContentUtils::SendMouseEvent(
     exitFrom = Some(WidgetMouseEvent::eChild);
   } else if (aType.EqualsLiteral("mousecancel")) {
     msg = eMouseExitFromWidget;
-    exitFrom = Some(WidgetMouseEvent::eTopLevel);
+    exitFrom = Some(XRE_IsParentProcess() ? WidgetMouseEvent::eTopLevel
+                                          : WidgetMouseEvent::ePuppet);
   } else if (aType.EqualsLiteral("mouselongtap")) {
     msg = eMouseLongTap;
   } else if (aType.EqualsLiteral("contextmenu")) {

dom/events/EventStateManager.cpp

@@ -646,10 +646,11 @@ nsresult EventStateManager::PreHandleEvent(nsPresContext* aPresContext,
       // above, at eMouseEnterIntoWidget case.
       aEvent->StopCrossProcessForwarding();
 
-      // If the event is not a top-level window exit, then it's not
-      // really an exit --- we may have traversed widget boundaries but
-      // we're still in our toplevel window.
-      if (mouseEvent->mExitFrom.value() != WidgetMouseEvent::eTopLevel) {
+      // If the event is not a top-level window or puppet widget exit, then it's
+      // not really an exit --- we may have traversed widget boundaries but
+      // we're still in our toplevel window or puppet widget.
+      if (mouseEvent->mExitFrom.value() != WidgetMouseEvent::eTopLevel &&
+          mouseEvent->mExitFrom.value() != WidgetMouseEvent::ePuppet) {
         // Treat it as a synthetic move so we don't generate spurious
         // "exit" or "move" events.  Any necessary "out" or "over" events
         // will be generated by GenerateMouseEnterExit
@@ -657,10 +658,14 @@ nsresult EventStateManager::PreHandleEvent(nsPresContext* aPresContext,
         mouseEvent->mReason = WidgetMouseEvent::eSynthesized;
         // then fall through...
       } else {
+        MOZ_ASSERT_IF(XRE_IsParentProcess(), mouseEvent->mExitFrom.value() ==
+                                                 WidgetMouseEvent::eTopLevel);
+        MOZ_ASSERT_IF(XRE_IsContentProcess(), mouseEvent->mExitFrom.value() ==
+                                                  WidgetMouseEvent::ePuppet);
         // We should synthetize corresponding pointer events
         GeneratePointerEnterExit(ePointerLeave, mouseEvent);
         GenerateMouseEnterExit(mouseEvent);
-        // This is a window level mouse exit event and should stop here
+        // This is really an exit and should stop here
         aEvent->mMessage = eVoidEvent;
         break;
       }
@@ -4220,11 +4225,11 @@ nsIFrame* EventStateManager::DispatchMouseOrPointerEvent(
     // event to the remote frame.
     if (IsTopLevelRemoteTarget(targetContent)) {
       if (aMessage == eMouseOut) {
-        // For remote content, send a "top-level" widget mouse exit event.
+        // For remote content, send a puppet widget mouse exit event.
         UniquePtr<WidgetMouseEvent> remoteEvent =
             CreateMouseOrPointerWidgetEvent(aMouseEvent, eMouseExitFromWidget,
                                             relatedContent);
-        remoteEvent->mExitFrom = Some(WidgetMouseEvent::eTopLevel);
+        remoteEvent->mExitFrom = Some(WidgetMouseEvent::ePuppet);
 
         // mCurrentTarget is set to the new target, so we must reset it to the
         // old target and then dispatch a cross-process event. (mCurrentTarget

layout/base/PresShell.cpp

@@ -6984,9 +6984,11 @@ nsresult PresShell::EventHandler::HandleEventUsingCoordinates(
   }
 
   WidgetMouseEvent* mouseEvent = aGUIEvent->AsMouseEvent();
-  bool isWindowLevelMouseExit = (aGUIEvent->mMessage == eMouseExitFromWidget) &&
-                                (mouseEvent && mouseEvent->mExitFrom.value() ==
-                                                   WidgetMouseEvent::eTopLevel);
+  bool isWindowLevelMouseExit =
+      (aGUIEvent->mMessage == eMouseExitFromWidget) &&
+      (mouseEvent &&
+       (mouseEvent->mExitFrom.value() == WidgetMouseEvent::eTopLevel ||
+        mouseEvent->mExitFrom.value() == WidgetMouseEvent::ePuppet));
 
   // Get the frame at the event point. However, don't do this if we're
   // capturing and retargeting the event because the captured frame will

widget/MouseEvents.h

@@ -190,8 +190,8 @@ class WidgetMouseEvent : public WidgetMouseEventBase,
     eControlClick
   };
 
-  typedef bool ExitFromType;
-  enum ExitFrom : ExitFromType { eChild, eTopLevel };
+  typedef uint8_t ExitFromType;
+  enum ExitFrom : ExitFromType { eChild, eTopLevel, ePuppet };
 
  protected:
   WidgetMouseEvent()
@@ -267,8 +267,8 @@ class WidgetMouseEvent : public WidgetMouseEventBase,
   ContextMenuTrigger mContextMenuTrigger;
 
   // mExitFrom contains a value only when mMessage is eMouseExitFromWidget.
-  // This indicates if the mouse cursor exits from a top level widget or
-  // a child widget.
+  // This indicates if the mouse cursor exits from a top level platform widget,
+  // a child widget or a puppet widget.
   Maybe<ExitFrom> mExitFrom;
 
   // Whether the event should ignore scroll frame bounds during dispatch.