Updates subpixel positioning and hinting when DSF is changed

ui/gfx/font_render_params.h

 // Copyright 2014 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_RENDER_PARAMS_H_
 #define UI_GFX_FONT_RENDER_PARAMS_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 64 matching lines @@
 
   // Requested font families, or empty if unset.
   std::vector<std::string> families;
 
   // Font size in pixels or points, or 0 if unset.
   int pixel_size;
   int point_size;
 
   // gfx::Font::FontStyle bit field, or -1 if unset.
   int style;
+
+  // The device scale factor of the display, or 0 if unset.
+  float device_scale_factor;
 };
 
 // Returns the appropriate parameters for rendering the font described by
 // |query|. If |family_out| is non-NULL, it will be updated to contain the
 // recommended font family from |query.families|.
 GFX_EXPORT FontRenderParams GetFontRenderParams(
     const FontRenderParamsQuery& query,
     std::string* family_out);
 
 // Clears GetFontRenderParams()'s cache. Intended to be called by tests that are
 // changing Fontconfig's configuration.
 // TODO(derat): This is only defined for Linux, but OS_LINUX doesn't seem to be
 // set when font_render_params_linux_unittest.cc includes this header. Figure
 // out what's going on here.
 GFX_EXPORT void ClearFontRenderParamsCacheForTest();
 
 #if defined(OS_CHROMEOS)
+// Gets the device scale factor to query the FontRenderParams.
+float GetFontRenderParamsDeviceScaleFactor();
+
 // Sets the device scale factor for FontRenderParams to decide
 // if it should enable subpixel positioning.
 GFX_EXPORT void SetFontRenderParamsDeviceScaleFactor(
     float device_scale_factor);
 #endif
 
 }  // namespace gfx
 
 #endif  // UI_GFX_FONT_RENDER_PARAMS_H_