Stack preview back at top after an active contents switch.

chrome/browser/ui/views/frame/browser_view.cc

 // Copyright 2012 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/frame/browser_view.h"
 
 #include <algorithm>
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
@@ skipping 1635 matching lines @@
         browser_->search_model()->mode());
   }
   UpdateUIForContents(new_contents);
 
   // Layout for DevTools _before_ setting the main WebContents to avoid
   // toggling the size of the main WebContents.
   UpdateDevToolsForContents(new_contents);
 
   if (change_tab_contents) {
     contents_container_->SetWebContents(new_contents);
-#if defined(USE_AURA)
-    // Put the Instant preview back on top in case it is showing custom new tab
-    // page content.
-    if (contents_->preview_web_contents()) {
-      ui::Layer* preview_layer =
-          contents_->preview_web_contents()->GetNativeView()->layer();
-      preview_layer->parent()->StackAtTop(preview_layer);
-    }
-#endif
+    contents_->MaybeStackPreviewAtTop();
   }
 
   if (!browser_->tab_strip_model()->closing_all() && GetWidget()->IsActive() &&
       GetWidget()->IsVisible()) {
     // We only restore focus if our window is visible, to avoid invoking blur
     // handlers when we are eventually shown.
     new_contents->GetView()->RestoreFocus();
   }
 
   // Update all the UI bits.
@@ skipping 1105 matching lines @@
     modal_browser->window()->Activate();
   }
 
   AppModalDialogQueue::GetInstance()->ActivateModalDialog();
 }
 
 void BrowserView::MaybeStackBookmarkBarAtTop() {
   if (bookmark_bar_view_.get())
     bookmark_bar_view_->MaybeStackAtTop();
 }