Bug 1958711 - Remove reentrancy from nsWindow::OnPaint. r=win-reviewers,handyman

I don't think this should be needed. Painting shouldn't trigger new
invalidations (and nowadays most of the actual compositing doesn't
happen here anyways).

Differential Revision: https://phabricator.services.mozilla.com/D244531

widget/windows/nsWindow.cpp

@@ -5025,7 +5025,7 @@ bool nsWindow::ProcessMessageInternal(UINT msg, WPARAM& wParam, LPARAM& lParam,
       break;
 
     case WM_PAINT:
-      *aRetValue = (int)OnPaint(0);
+      *aRetValue = (int)OnPaint();
       result = true;
       break;
 

widget/windows/nsWindow.h

@@ -606,7 +606,7 @@ class nsWindow final : public nsBaseWidget,
   bool OnGesture(WPARAM wParam, LPARAM lParam);
   bool OnTouch(WPARAM wParam, LPARAM lParam);
   bool OnHotKey(WPARAM wParam, LPARAM lParam);
-  bool OnPaint(uint32_t aNestingLevel);
+  bool OnPaint();
   void OnWindowPosChanging(WINDOWPOS* info);
   void OnWindowPosChanged(WINDOWPOS* wp);
   void OnSysColorChanged();

widget/windows/nsWindowGfx.cpp

@@ -127,7 +127,7 @@ void nsWindow::ForcePresent() {
   }
 }
 
-bool nsWindow::OnPaint(uint32_t aNestingLevel) {
+bool nsWindow::OnPaint() {
   struct FallbackPaintContext {
     RefPtr<gfxASurface> mTargetSurface;
     RefPtr<DrawTarget> mDt;
@@ -209,9 +209,6 @@ bool nsWindow::OnPaint(uint32_t aNestingLevel) {
       if (nsIWidgetListener* listener = GetPaintListener()) {
         listener->DidPaintWindow();
       }
-      if (aNestingLevel == 0 && ::GetUpdateRect(mWnd, nullptr, false)) {
-        OnPaint(1);
-      }
     }
   });