Rework gfx::Font by moving platform-specific code into inner classes....

gfx/platform_font_mac.h

Index: gfx/platform_font_mac.h
===================================================================
--- gfx/platform_font_mac.h	(revision 0)
+++ gfx/platform_font_mac.h	(revision 0)
@@ -0,0 +1,57 @@
+// 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.
+
+#ifndef GFX_PLATFORM_FONT_MAC_
+#define GFX_PLATFORM_FONT_MAC_
+#pragma once
+
+#include "gfx/platform_font.h"
+
+namespace gfx {
+
+class PlatformFontMac : public PlatformFont {
+ public:
+  PlatformFontMac();
+  explicit PlatformFontMac(const Font& other);
+  explicit PlatformFontMac(NativeFont native_font);
+  PlatformFontMac(const std::wstring& font_name,
+                  int font_size);
+
+  // Overridden from PlatformFont:
+  virtual Font DeriveFont(int size_delta, int style) const;
+  virtual int GetHeight() const;
+  virtual int GetBaseline() const;
+  virtual int GetAverageCharacterWidth() const;
+  virtual int GetStringWidth(const std::wstring& text) const;
+  virtual int GetExpectedTextWidth(int length) const;
+  virtual int GetStyle() const;
+  virtual const std::wstring& GetFontName() const;
+  virtual int GetFontSize() const;
+  virtual NativeFont GetNativeFont() const;
+
+ private:
+  PlatformFontMac(const std::wstring& font_name, int font_size, int style);
+  virtual ~PlatformFontMac() {}
+
+  // Initialize the object with the specified parameters.
+  void InitWithNameSizeAndStyle(const std::wstring& font_name,
+                                int font_size,
+                                int style);
+
+  // Calculate and cache the font metrics.
+  void CalculateMetrics();
+
+  std::wstring font_name_;
+  int font_size_;
+  int style_;
+
+  // Cached metrics, generated at construction
+  int height_;
+  int ascent_;
+  int average_width_;
+};
+
+}  // namespace gfx
+
+#endif  // GFX_PLATFORM_FONT_MAC_