[MacViews] Left-align control labels as on other platforms.

ui/views/layout/layout_constants.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_VIEWS_LAYOUT_LAYOUT_CONSTANTS_H_
 #define UI_VIEWS_LAYOUT_LAYOUT_CONSTANTS_H_
 
 #include "build/build_config.h"
 #include "ui/views/layout/grid_layout.h"
 
@@ skipping 63 matching lines @@
 const int kRelatedButtonHSpacing = 6;
 
 // Indent of checkboxes relative to related text.
 const int kCheckboxIndent = 10;
 
 // Horizontal spacing between the end of an item (i.e. an icon or a checkbox)
 // and the start of its corresponding text.
 const int kItemLabelSpacing = 10;
 
 // Horizontal alignment used for a control's introductory label in a GridLayout.
-#if defined(OS_MACOSX)
-const GridLayout::Alignment kControlLabelGridAlignment = GridLayout::TRAILING;
-#else
 const GridLayout::Alignment kControlLabelGridAlignment = GridLayout::LEADING;
-#endif
 
 }  // namespace views
 
 #endif  // UI_VIEWS_LAYOUT_LAYOUT_CONSTANTS_H_