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 32 matching lines @@
   // Overridden from PlatformFont:
   Font DeriveFont(int size_delta, int style) const override;
   int GetHeight() const override;
   int GetBaseline() const override;
   int GetCapHeight() const override;
   int GetExpectedTextWidth(int length) const override;
   int GetStyle() const override;
   std::string GetFontName() const override;
   std::string GetActualFontNameForTesting() const override;
   int GetFontSize() const override;
-  const FontRenderParams& GetFontRenderParams() const override;
+  const FontRenderParams& GetFontRenderParams() override;
   NativeFont GetNativeFont() const override;
 
  private:
   // Create a new instance of this object with the specified properties. Called
   // from DeriveFont.
   PlatformFontPango(const skia::RefPtr<SkTypeface>& typeface,
                     const std::string& name,
                     int size_pixels,
                     int style,
                     const FontRenderParams& params);
@@ skipping 23 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)
+  float device_scale_factor_;
+#endif
 
   // Information describing how the font should be rendered.
   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_