Remove native_stack accessor from StackedPanelCollection

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

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/panels/panel_stack_view.h"
 
 #include "base/logging.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/panels/panel.h"
@@ skipping 172 matching lines @@
 #endif
 }
 
 void PanelStackView::UpdateWindowOwnerForTaskbarIconAppearance(Panel* panel) {
 #if defined(OS_WIN)
   HWND panel_window = views::HWNDForWidget(
       static_cast<PanelView*>(panel->native_panel())->window());
 
   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
   // bit needs to be cleared.
   int value = ::GetWindowLong(panel_window, GWL_EXSTYLE);
   ::SetWindowLong(
       panel_window,
       GWL_EXSTYLE,
       stack_window ? (value & ~WS_EX_APPWINDOW) : (value | WS_EX_APPWINDOW));
 
@@ skipping 27 matching lines @@
             stacked_collection_->panels().begin();
         iter != stacked_collection_->panels().end(); ++iter) {
     Panel* panel = *iter;
     native_panel_windows.push_back(
         views::HWNDForWidget(
             static_cast<PanelView*>(panel->native_panel())->window()));
   }
   thumbnailer_->Start(native_panel_windows);
 #endif
 }