Make gfx::Rect::CenterPoint() return the correct center point....

ui/gfx/rect.cc

 // Copyright (c) 2010 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.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #elif defined(OS_MACOSX)
 #include <CoreGraphics/CGGeometry.h>
@@ skipping 213 matching lines @@
   int new_x = x();
   int new_y = y();
   int new_width = width();
   int new_height = height();
   AdjustAlongAxis(rect.x(), rect.width(), &new_x, &new_width);
   AdjustAlongAxis(rect.y(), rect.height(), &new_y, &new_height);
   return Rect(new_x, new_y, new_width, new_height);
 }
 
 Point Rect::CenterPoint() const {
-  return Point(x() + (width() + 1) / 2, y() + (height() + 1) / 2);
+  return Point(x() + (width() - 1) / 2, y() + (height() - 1) / 2);
 }
 
 Rect Rect::Center(const gfx::Size& size) const {
   int new_width = std::min(width(), size.width());
   int new_height = std::min(height(), size.height());
   int new_x = x() + (width() - new_width) / 2;
   int new_y = y() + (height() - new_height) / 2;
   return Rect(new_x, new_y, new_width, new_height);
 }
 
 bool Rect::SharesEdgeWith(const gfx::Rect& 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()));
 }
 
 std::ostream& operator<<(std::ostream& out, const gfx::Rect& r) {
   return out << r.origin() << " " << r.size();
 }
 
 }  // namespace gfx