Updates subpixel positioning and hinting when DSF is changed

ui/gfx/font_render_params.cc

 // 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.
 
 #include "ui/gfx/font_render_params.h"
 
 namespace gfx {
 
+namespace {
+
+FontRenderParamsRewriter* g_instance = nullptr;
+}
+
+// static
+FontRenderParamsRewriter* FontRenderParamsRewriter::GetInstance() {
+  return g_instance;
+}
+
+// static
+void FontRenderParamsRewriter::SetInstance(FontRenderParamsRewriter* instance) {
+  Shutdown();
+  g_instance = instance;
+}
+
+// static
+void FontRenderParamsRewriter::Shutdown() {
+  if (g_instance)
+    delete g_instance;
+  g_instance = nullptr;
+}
+
+FontRenderParamsRewriter::~FontRenderParamsRewriter() {
+}
+
 FontRenderParams::FontRenderParams()
     : antialiasing(true),
       subpixel_positioning(true),
       autohinter(false),
       use_bitmaps(false),
       hinting(HINTING_MEDIUM),
       subpixel_rendering(SUBPIXEL_RENDERING_NONE) {
 }
 
 FontRenderParams::~FontRenderParams() {}
 
 FontRenderParamsQuery::FontRenderParamsQuery(bool for_web_contents)
     : for_web_contents(for_web_contents),
       pixel_size(0),
       point_size(0),
       style(-1) {
 }
 
 FontRenderParamsQuery::~FontRenderParamsQuery() {}
 
+FontRenderParams GetCurrentFontRenderParams(const FontRenderParamsQuery& query,
+                                            std::string* family_out) {
+  FontRenderParams params = GetSystemFontRenderParams(query, family_out);
+  if (g_instance)
+    g_instance->RewriteParams(&params);
+  return params;
+}
+
 }  // namespace gfx