Improve omnibox accessibility on Windows.

chrome/browser/ui/gtk/omnibox/omnibox_view_gtk.cc

 // Copyright (c) 2011 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/gtk/omnibox/omnibox_view_gtk.h"
 
 #include <gdk/gdkkeysyms.h>
 #include <gtk/gtk.h>
 
 #include <algorithm>
@@ skipping 573 matching lines @@
   // Returns true if the |text_buffer_| is empty.
   return gtk_text_iter_equal(&start, &sel_start) &&
       gtk_text_iter_equal(&end, &sel_end);
 }
 
 bool OmniboxViewGtk::DeleteAtEndPressed() {
   return delete_at_end_pressed_;
 }
 
 void OmniboxViewGtk::GetSelectionBounds(string16::size_type* start,
-                                        string16::size_type* end) {
+                                        string16::size_type* end) const {
   CharRange selection = GetSelection();
   *start = static_cast<size_t>(selection.cp_min);
   *end = static_cast<size_t>(selection.cp_max);
 }
 
 void OmniboxViewGtk::SelectAll(bool reversed) {
   // SelectAll() is invoked as a side effect of other actions (e.g.  switching
   // tabs or hitting Escape) in autocomplete_edit.cc, so we don't update the
   // PRIMARY selection here.
   SelectAllInternal(reversed, false);
@@ skipping 1782 matching lines @@
   // baseline, so we need to move the |instant_view_| down to make sure it
   // has the same baseline as the |text_view_|.
   PangoLayout* layout = gtk_label_get_layout(GTK_LABEL(instant_view_));
   int height;
   pango_layout_get_size(layout, NULL, &height);
   PangoLayoutIter* iter = pango_layout_get_iter(layout);
   int baseline = pango_layout_iter_get_baseline(iter);
   pango_layout_iter_free(iter);
   g_object_set(instant_anchor_tag_, "rise", baseline - height, NULL);
 }