Add a flag use_software_compositing to the Widget::InitParams structure.

chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc

 // Copyright (c) 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/omnibox/omnibox_popup_contents_view.h"
 
 #include <algorithm>
 
 #include "chrome/browser/search/search.h"
 #include "chrome/browser/themes/theme_properties.h"
@@ skipping 216 matching lines @@
   // last few pixels to get to one visible result.
   if (new_target_bounds.height() != target_bounds_.height())
     size_animation_.Reset();
   target_bounds_ = new_target_bounds;
 
   if (popup_ == NULL) {
     views::Widget* popup_parent = location_bar_view_->GetWidget();
 
     // If the popup is currently closed, we need to create it.
     popup_ = (new AutocompletePopupWidget)->AsWeakPtr();
-    // On Windows use TYPE_MENU to ensure that this window uses the software
-    // compositor which avoids the UI thread blocking issue during command
-    // buffer creation. We can revert this change once http://crbug.com/125248
-    // is fixed.
+
+    views::Widget::InitParams params(views::Widget::InitParams::TYPE_POPUP);
 #if defined(OS_WIN)
-    views::Widget::InitParams params(views::Widget::InitParams::TYPE_MENU);
-    // The menu style assumes a top most window. We don't want that in this
-    // case.
-    params.keep_on_top = false;
-#else
-    views::Widget::InitParams params(views::Widget::InitParams::TYPE_POPUP);
+    // On Windows use the software compositor to ensure that we don't block
+    // the UI thread blocking issue during command buffer creation. We can
+    // revert this change once http://crbug.com/125248 is fixed.
+    params.force_software_compositing = true;
 #endif
     params.opacity = views::Widget::InitParams::TRANSLUCENT_WINDOW;
     params.parent = popup_parent->GetNativeView();
     params.bounds = GetPopupBounds();
     params.context = popup_parent->GetNativeWindow();
     popup_->Init(params);
     // Third-party software such as DigitalPersona identity verification can
     // hook the underlying window creation methods and use SendMessage to
     // synchronously change focus/activation, resulting in the popup being
     // destroyed by the time control returns here.  Bail out in this case to
@@ skipping 267 matching lines @@
   size_t index = GetIndexForPoint(event.location());
   if (!HasMatchAt(index))
     return;
   omnibox_view_->OpenMatch(model_->result().match_at(index), disposition,
                            GURL(), base::string16(), index);
 }
 
 OmniboxResultView* OmniboxPopupContentsView::result_view_at(size_t i) {
   return static_cast<OmniboxResultView*>(child_at(static_cast<int>(i)));
 }