Always aligns text at vertically center (Textfield, Label).

ui/gfx/font.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_GFX_FONT_H_
 #define UI_GFX_FONT_H_
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
 #include "base/strings/string16.h"
 #include "ui/gfx/gfx_export.h"
 #include "ui/gfx/native_widget_types.h"
 
 namespace gfx {
 
 class PlatformFont;
 
 // Font provides a wrapper around an underlying font. Copy and assignment
 // operators are explicitly allowed, and cheap.
+//
+// Figure of font metrics:
+//   +--------+-------------------+------------------+
+//   |        |                   | internal leading |
+//   |        | ascent (baseline) +------------------+
+//   | height |                   | cap height       |
+//   |        |-------------------+------------------+
+//   |        | descent (height - baseline)          |
+//   +--------+--------------------------------------+
 class GFX_EXPORT Font {
  public:
   // The following constants indicate the font style.
   enum FontStyle {
     NORMAL = 0,
     BOLD = 1,
     ITALIC = 2,
     UNDERLINE = 4,
   };
 
@@ skipping 77 matching lines @@
   PlatformFont* platform_font() const { return platform_font_.get(); }
 
  private:
   // Wrapped platform font implementation.
   scoped_refptr<PlatformFont> platform_font_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_FONT_H_