Add GetDefaultIndex() to ComboboxModel.

ui/views/controls/combobox/combobox.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 "ui/views/controls/combobox/combobox.h"
 
 #include "base/logging.h"
 #include "base/utf_string_conversions.h"
 #include "ui/base/accessibility/accessible_view_state.h"
 #include "ui/base/events/event.h"
 #include "ui/base/keycodes/keyboard_codes.h"
 #include "ui/base/models/combobox_model.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/views/controls/combobox/combobox_listener.h"
 #include "ui/views/controls/native/native_view_host.h"
 #include "ui/views/widget/widget.h"
 
 namespace views {
 
 // static
 const char Combobox::kViewClassName[] = "views/Combobox";
 
 ////////////////////////////////////////////////////////////////////////////////
 // Combobox, public:
 
 Combobox::Combobox(ui::ComboboxModel* model)
     : native_wrapper_(NULL),
       model_(model),
       listener_(NULL),
-      selected_index_(0) {
-  DCHECK(model);
+      selected_index_(model_->GetDefaultIndex()) {
   set_focusable(true);
 }
 
 Combobox::~Combobox() {
 }
 
 // static
 const gfx::Font& Combobox::GetFont() {
   ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
   return rb.GetFont(ui::ResourceBundle::BaseFont);
@@ skipping 106 matching lines @@
     native_wrapper_->UpdateSelectedIndex();
     native_wrapper_->UpdateEnabled();
   }
 }
 
 std::string Combobox::GetClassName() const {
   return kViewClassName;
 }
 
 }  // namespace views