Revert "Bug 1882358 Part 3: Remove nsIWidget::IsResizingNativeWidget, which is no longer used. r=nical"

This reverts commit a238e0a.

Author: K4sum1

widget/nsIWidget.h

@@ -778,6 +778,10 @@ class nsIWidget : public nsISupports {
   virtual void Resize(double aX, double aY, double aWidth, double aHeight,
                       bool aRepaint) = 0;
 
+  virtual mozilla::Maybe<bool> IsResizingNativeWidget() {
+    return mozilla::Nothing();
+  }
+
   /**
    * Resize the widget so that the inner client area has the given size.
    *

widget/windows/nsWindow.cpp

@@ -2174,6 +2174,13 @@ void nsWindow::Resize(double aX, double aY, double aWidth, double aHeight,
   if (aRepaint) Invalidate();
 }
 
+mozilla::Maybe<bool> nsWindow::IsResizingNativeWidget() {
+  if (mResizeState == RESIZING) {
+    return Some(true);
+  }
+  return Some(false);
+}
+
 /**************************************************************
  *
  * SECTION: Window Z-order and state.

widget/windows/nsWindow.h

@@ -175,6 +175,7 @@ class nsWindow final : public nsBaseWidget {
   void Resize(double aWidth, double aHeight, bool aRepaint) override;
   void Resize(double aX, double aY, double aWidth, double aHeight,
               bool aRepaint) override;
+  mozilla::Maybe<bool> IsResizingNativeWidget() override;
   void PlaceBehind(nsTopLevelWidgetZPlacement aPlacement, nsIWidget* aWidget,
                    bool aActivate) override;
   void SetSizeMode(nsSizeMode aMode) override;