Ensure that NativeWidgetWin::OnPaint calls ValidateRect; workaround for crbug.com/93530.

views/widget/native_widget_win.cc

Index: views/widget/native_widget_win.cc
diff --git a/views/widget/native_widget_win.cc b/views/widget/native_widget_win.cc
index e31196e0b67a936a1eadbfc9748978aca0b9abaf..9f93bc4e3ece309c4df7733a573c28bc1b04ed64 100644
--- a/views/widget/native_widget_win.cc
+++ b/views/widget/native_widget_win.cc
@@ -1774,6 +1774,10 @@ void NativeWidgetWin::OnPaint(HDC dc) {
           gfx::CanvasPaint::CreateCanvasPaint(hwnd()));
       delegate_->OnNativeWidgetPaint(canvas->AsCanvas());
     }
+  } else {
+    // TODO(msw): Find a better solution for this crbug.com/93530 workaround.
+    // Some scenarios otherwise fail to validate minimized app/popup windows.
+    ValidateRect(hwnd(), NULL);
   }
 }