ui: Change ListModel to operate in size_t instead of int.

ui/app_list/app_list_model_view.h

 // 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.
 
 #ifndef UI_APP_LIST_APP_LIST_MODEL_VIEW_H_
 #define UI_APP_LIST_APP_LIST_MODEL_VIEW_H_
 #pragma once
 
 #include "ui/app_list/app_list_export.h"
 #include "ui/app_list/pagination_model_observer.h"
@@ skipping 53 matching lines @@
   void SetSelectedItemByIndex(int index);
 
   // Overridden from views::View:
   virtual gfx::Size GetPreferredSize() OVERRIDE;
   virtual void Layout() OVERRIDE;
   virtual bool OnKeyPressed(const views::KeyEvent& event) OVERRIDE;
   virtual bool OnKeyReleased(const views::KeyEvent& event) OVERRIDE;
   virtual void OnPaintFocusBorder(gfx::Canvas* canvas) OVERRIDE;
 
   // Overridden from ListModelObserver:
-  virtual void ListItemsAdded(int start, int count) OVERRIDE;
-  virtual void ListItemsRemoved(int start, int count) OVERRIDE;
-  virtual void ListItemsChanged(int start, int count) OVERRIDE;
+  virtual void ListItemsAdded(size_t start, size_t count) OVERRIDE;
+  virtual void ListItemsRemoved(size_t start, size_t count) OVERRIDE;
+  virtual void ListItemsChanged(size_t start, size_t count) OVERRIDE;
 
   // Overridden from PaginationModelObserver:
   virtual void TotalPagesChanged() OVERRIDE;
   virtual void SelectedPageChanged(int old_selected, int new_selected) OVERRIDE;
 
   AppListModel* model_;  // Owned by parent AppListView.
   views::ButtonListener* listener_;
   PaginationModel* pagination_model_;  // Owned by AppListView.
 
   bool fixed_layout_;
   gfx::Size icon_size_;
   int cols_;
   int rows_per_page_;
 
   int selected_item_index_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListModelView);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_APP_LIST_MODEL_VIEW_H_