Updates subpixel positioning and hinting when DSF is changed

ui/gfx/platform_font_pango.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_PANGO_H_
 #define UI_GFX_PLATFORM_FONT_PANGO_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 76 matching lines @@
   // The average width of a character, initialized and cached if needed.
   double GetAverageWidth() const;
 
   skia::RefPtr<SkTypeface> typeface_;
 
   // Additional information about the face.
   // Skia actually expects a family name and not a font name.
   std::string font_family_;
   int font_size_pixels_;
   int style_;
+#if defined(OS_CHROMEOS)
+  // mutable to be updated in GetFontRenderParams().
+  mutable float device_scale_factor_;

[Daniel Erat, 2014/12/12 15:54:58]

instead of making these mutable, would you mind just making
GetFontRenderParams() be non-const?

[Jun Mukai, 2014/12/12 19:40:12]

Done.

+#endif
 
-  // Information describing how the font should be rendered.
-  FontRenderParams font_render_params_;
+  // Information describing how the font should be rendered. This parameter is
+  // mutable to update in GetFontRenderParams().
+  mutable FontRenderParams font_render_params_;
 
   // Cached metrics, generated at construction.
   int ascent_pixels_;
   int height_pixels_;
   int cap_height_pixels_;
 
   // The pango metrics are much more expensive so we wait until we need them
   // to compute them.
   bool pango_metrics_inited_;
   double average_width_pixels_;
 
   // The default font, used for the default constructor.
   static Font* default_font_;
 
 #if defined(OS_CHROMEOS)
   // A Pango font description.
   static std::string* default_font_description_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(PlatformFontPango);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_PLATFORM_FONT_PANGO_H_