Remove native_stack accessor from StackedPanelCollection

chrome/browser/ui/views/panels/panel_stack_view.cc

Index: chrome/browser/ui/views/panels/panel_stack_view.cc
diff --git a/chrome/browser/ui/views/panels/panel_stack_view.cc b/chrome/browser/ui/views/panels/panel_stack_view.cc
index 394cdcec247e13c3b4e691ac9ad93a59d0a216c0..e39f2a3dc1d1a28b7cc7d239df83f09640d71c86 100644
--- a/chrome/browser/ui/views/panels/panel_stack_view.cc
+++ b/chrome/browser/ui/views/panels/panel_stack_view.cc
@@ -190,10 +190,8 @@ void PanelStackView::UpdateWindowOwnerForTaskbarIconAppearance(Panel* panel) {
 
   HWND stack_window = NULL;
   StackedPanelCollection* stack = panel->stack();
-  if (stack) {
-    stack_window = views::HWNDForWidget(
-        static_cast<PanelStackView*>(stack->native_stack())->window_);
-  }
+  if (stack)
+    stack_window = views::HWNDForWidget(window_);
 
   // The extended style WS_EX_APPWINDOW is used to force a top-level window onto
   // the taskbar. In order for multiple stacked panels to appear as one, this