Bug 1719150 - Push delayed mouse event to the right pres shell. r=smaug

Otherwise if we get an event targeting a different suppressed pres shell
while we're unsuppressing we might get stuck delaying the event over and
over, see the links in comment 33.

Not sure how to get a repro for this, the patch is written based on the
pernosco session, but suggestions welcome.

Differential Revision: https://phabricator.services.mozilla.com/D130100

layout/base/PresShell.cpp

@@ -7598,7 +7598,7 @@ bool PresShell::EventHandler::MaybeDiscardOrDelayKeyboardEvent(
   } else if (!mPresShell->mNoDelayedKeyEvents) {
     UniquePtr<DelayedKeyEvent> delayedKeyEvent =
         MakeUnique<DelayedKeyEvent>(aGUIEvent->AsKeyboardEvent());
-    PushDelayedEventIntoQueue(std::move(delayedKeyEvent));
+    mPresShell->mDelayedEvents.AppendElement(std::move(delayedKeyEvent));
   }
   aGUIEvent->mFlags.mIsSuppressedOrDelayed = true;
   return true;
@@ -7623,9 +7623,11 @@ bool PresShell::EventHandler::MaybeDiscardOrDelayMouseEvent(
                     aGUIEvent->mMessage != eMouseMove,
                 !InputTaskManager::Get()->IsSuspended());
 
+  RefPtr<PresShell> ps = aFrameToHandleEvent->PresShell();
+
   if (aGUIEvent->mMessage == eMouseDown) {
-    mPresShell->mNoDelayedMouseEvents = true;
-  } else if (!mPresShell->mNoDelayedMouseEvents &&
+    ps->mNoDelayedMouseEvents = true;
+  } else if (!ps->mNoDelayedMouseEvents &&
              (aGUIEvent->mMessage == eMouseUp ||
               // contextmenu is triggered after right mouseup on Windows and
               // right mousedown on other platforms.
@@ -7633,7 +7635,7 @@ bool PresShell::EventHandler::MaybeDiscardOrDelayMouseEvent(
               aGUIEvent->mMessage == eMouseExitFromWidget)) {
     UniquePtr<DelayedMouseEvent> delayedMouseEvent =
         MakeUnique<DelayedMouseEvent>(aGUIEvent->AsMouseEvent());
-    PushDelayedEventIntoQueue(std::move(delayedMouseEvent));
+    ps->mDelayedEvents.AppendElement(std::move(delayedMouseEvent));
   }
 
   // If there is a suppressed event listener associated with the document,

layout/base/PresShell.h

@@ -2742,10 +2742,6 @@ class PresShell final : public nsStubDocumentObserver,
     already_AddRefed<PresShell> GetParentPresShellForEventHandling() {
       return mPresShell->GetParentPresShellForEventHandling();
     }
-    void PushDelayedEventIntoQueue(UniquePtr<DelayedEvent>&& aDelayedEvent) {
-      mPresShell->mDelayedEvents.AppendElement(std::move(aDelayedEvent));
-    }
-
     OwningNonNull<PresShell> mPresShell;
     AutoCurrentEventInfoSetter* mCurrentEventInfoSetter;
     static TimeStamp sLastInputCreated;