Revert 160976 - The center of a rect is x+width/2, y+height/2

ui/gfx/rect_base_impl.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.
 
 #include "ui/gfx/rect_base.h"
 
 #include "base/logging.h"
 #include "base/stringprintf.h"
 
 // This file provides the implementation for RectBaese template and
@@ skipping 250 matching lines @@
   return Class(new_x, new_y, new_width, new_height);
 }
 
 template<typename Class,
          typename PointClass,
          typename SizeClass,
          typename InsetsClass,
          typename Type>
 PointClass RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::
     CenterPoint() const {
-  return PointClass(x() + width() / 2, y() + height() / 2);
+  return PointClass(x() + (width() - 1) / 2, y() + (height() - 1) / 2);
 }
 
 template<typename Class,
          typename PointClass,
          typename SizeClass,
          typename InsetsClass,
          typename Type>
 Class RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::Center(
     const SizeClass& size) const {
   Type new_width = std::min(width(), size.width());
@@ skipping 27 matching lines @@
          typename Type>
 bool RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::SharesEdgeWith(
     const Class& rect) const {
   return (y() == rect.y() && height() == rect.height() &&
              (x() == rect.right() || right() == rect.x())) ||
          (x() == rect.x() && width() == rect.width() &&
              (y() == rect.bottom() || bottom() == rect.y()));
 }
 
 }  // namespace gfx