Fix CJK font linking size on Windows XP.

ui/gfx/platform_font_win.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_PLATFORM_FONT_WIN_H_
 #define UI_GFX_PLATFORM_FONT_WIN_H_
 #pragma once
 
 #include <string>
 
@@ skipping 29 matching lines @@
   // performed other than clamping to a minimum font height if
   // |get_minimum_font_size_callback| is specified.
   typedef void (*AdjustFontCallback)(LOGFONT* lf);
   static AdjustFontCallback adjust_font_callback;
 
   // Returns the font name for the system locale. Some fonts, particularly
   // East Asian fonts, have different names per locale. If the localized font
   // name could not be retrieved, returns GetFontName().
   std::string GetLocalizedFontName() const;
 
+  // Returns a derived Font with the specified |style| and with height at most
+  // |height|. If the height and style of the receiver already match, it is
+  // returned. Otherwise, the returned Font will have the largest size such that
+  // its height is less than or equal to |height|.

[msw, 2012/04/26 21:04:42]

It's unclear (from the comment) why the resulting height might not exactly match
the argument height, is it worth mentioning why that's the case?

[Alexei Svitkine (slow), 2012/04/26 21:45:56]

I've expanded the comment to explain that.

+  Font DeriveFontWithHeight(int height, int style);
+
   // Overridden from PlatformFont:
   virtual Font DeriveFont(int size_delta, int style) const OVERRIDE;
   virtual int GetHeight() const OVERRIDE;
   virtual int GetBaseline() const OVERRIDE;
   virtual int GetAverageCharacterWidth() const OVERRIDE;
   virtual int GetStringWidth(const string16& text) const OVERRIDE;
   virtual int GetExpectedTextWidth(int length) const OVERRIDE;
   virtual int GetStyle() const OVERRIDE;
   virtual std::string GetFontName() const OVERRIDE;
   virtual int GetFontSize() const OVERRIDE;
   virtual NativeFont GetNativeFont() const OVERRIDE;
 
  private:
   virtual ~PlatformFontWin() {}
 
   // Chrome text drawing bottoms out in the Windows GDI functions that take an
   // HFONT (an opaque handle into Windows). To avoid lots of GDI object
   // allocation and destruction, Font indirectly refers to the HFONT by way of
   // an HFontRef. That is, every Font has an HFontRef, which has an HFONT.
   //
   // HFontRef is reference counted. Upon deletion, it deletes the HFONT.
   // By making HFontRef maintain the reference to the HFONT, multiple
   // HFontRefs can share the same HFONT, and Font can provide value semantics.
   class HFontRef : public base::RefCounted<HFontRef> {
    public:
     // This constructor takes control of the HFONT, and will delete it when
     // the HFontRef is deleted.
     HFontRef(HFONT hfont,
+             int font_size,
              int height,
              int baseline,
              int ave_char_width,
              int style);
 
     // Accessors
     HFONT hfont() const { return hfont_; }
     int height() const { return height_; }
     int baseline() const { return baseline_; }
     int ave_char_width() const { return ave_char_width_; }
@@ skipping 45 matching lines @@
   static HFontRef* base_font_ref_;
 
   // Indirect reference to the HFontRef, which references the underlying HFONT.
   scoped_refptr<HFontRef> font_ref_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_PLATFORM_FONT_WIN_H_