Add a ScopedPangoFontDescription helper class and use it.

ui/gfx/font.h

 // Copyright (c) 2011 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_
 #pragma once
 
 #include <string>
 
@@ skipping 21 matching lines @@
   // Creates a font with the default name and style.
   Font();
 
   // Creates a font that is a clone of another font object.
   Font(const Font& other);
   gfx::Font& operator=(const Font& other);
 
   // Creates a font from the specified native font.
   explicit Font(NativeFont native_font);
 
-  // Construct a Font object with the specified PlatformFont object. The Font
+  // Constructs a Font object with the specified PlatformFont object. The Font
   // object takes ownership of the PlatformFont object.
   explicit Font(PlatformFont* platform_font);
 
   // Creates a font with the specified name in UTF-8 and size in pixels.
   Font(const std::string& font_name, int font_size);
 
   ~Font();
 
   // Returns a new Font derived from the existing font.
   // |size_deta| is the size in pixels to add to the current font. For example,
@@ skipping 37 matching lines @@
 
   // Returns the font size in pixels.
   int GetFontSize() const;
 
   // Returns the native font handle.
   // Lifetime lore:
   // Windows: This handle is owned by the Font object, and should not be
   //          destroyed by the caller.
   // Mac:     The object is owned by the system and should not be released.
   // Gtk:     This handle is created on demand, and must be freed by calling
-  //          pango_font_description_free() when the caller is done using it.
+  //          pango_font_description_free() when the caller is done using it or
+  //          by using ScopedPangoFontDescription.
   NativeFont GetNativeFont() const;
 
   // Raw access to the underlying platform font implementation. Can be
   // static_cast to a known implementation type if needed.
   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_