Updates subpixel positioning and hinting when DSF is changed

ui/gfx/platform_font_pango.cc

 // 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.
 
 #include "ui/gfx/platform_font_pango.h"
 
 #include <pango/pango.h>
 
 #include <algorithm>
 #include <string>
@@ skipping 184 matching lines @@
   SkString family_name;
   typeface_->getFamilyName(&family_name);
   return family_name.c_str();
 }
 
 int PlatformFontPango::GetFontSize() const {
   return font_size_pixels_;
 }
 
 const FontRenderParams& PlatformFontPango::GetFontRenderParams() const {
+#if defined(OS_CHROMEOS)
+  float current_scale_factor = gfx::GetFontRenderParamsDeviceScaleFactor();
+  if (current_scale_factor != device_scale_factor_) {
+    FontRenderParamsQuery query(false);
+    query.families.push_back(font_family_);
+    query.pixel_size = font_size_pixels_;
+    query.style = style_;
+    query.device_scale_factor = current_scale_factor;
+    font_render_params_ = gfx::GetFontRenderParams(query, nullptr);
+    device_scale_factor_ = current_scale_factor;
+  }
+#endif
   return font_render_params_;
 }
 
 NativeFont PlatformFontPango::GetNativeFont() const {
   PangoFontDescription* pfd = pango_font_description_new();
   pango_font_description_set_family(pfd, GetFontName().c_str());
   // Set the absolute size to avoid overflowing UI elements.
   // pango_font_description_set_absolute_size() takes a size in Pango units.
   // There are PANGO_SCALE Pango units in one device unit.  Screen output
   // devices use pixels as their device units.
@@ skipping 38 matching lines @@
     int font_size_pixels,
     int style,
     const FontRenderParams& render_params) {
   DCHECK_GT(font_size_pixels, 0);
 
   font_family_ = font_family;
   typeface_ = typeface ? typeface : CreateSkTypeface(style, &font_family_);
 
   font_size_pixels_ = font_size_pixels;
   style_ = style;
+#if defined(OS_CHROMEOS)
+  device_scale_factor_ = gfx::GetFontRenderParamsDeviceScaleFactor();
+#endif
   font_render_params_ = render_params;
 
   SkPaint paint;
   SkPaint::FontMetrics metrics;
   PaintSetup(&paint);
   paint.getFontMetrics(&metrics);
   ascent_pixels_ = SkScalarCeilToInt(-metrics.fAscent);
   height_pixels_ = ascent_pixels_ + SkScalarCeilToInt(metrics.fDescent);
   cap_height_pixels_ = SkScalarCeilToInt(metrics.fCapHeight);
 
   pango_metrics_inited_ = false;
   average_width_pixels_ = 0.0f;
 }
 
 void PlatformFontPango::InitFromPlatformFont(const PlatformFontPango* other) {
   typeface_ = other->typeface_;
   font_family_ = other->font_family_;
   font_size_pixels_ = other->font_size_pixels_;
   style_ = other->style_;
   font_render_params_ = other->font_render_params_;
   ascent_pixels_ = other->ascent_pixels_;
   height_pixels_ = other->height_pixels_;
   cap_height_pixels_ = other->cap_height_pixels_;
   pango_metrics_inited_ = other->pango_metrics_inited_;
   average_width_pixels_ = other->average_width_pixels_;
+#if defined(OS_CHROMEOS)
+  device_scale_factor_ = other->device_scale_factor_;
+#endif
 }
 
 void PlatformFontPango::PaintSetup(SkPaint* paint) const {
   paint->setAntiAlias(false);
   paint->setSubpixelText(false);
   paint->setTextSize(font_size_pixels_);
   paint->setTypeface(typeface_.get());
   paint->setFakeBoldText((gfx::Font::BOLD & style_) && !typeface_->isBold());
   paint->setTextSkewX((gfx::Font::ITALIC & style_) && !typeface_->isItalic() ?
                       -SK_Scalar1/4 : 0);
@@ skipping 39 matching lines @@
   return new PlatformFontPango(native_font);
 }
 
 // static
 PlatformFont* PlatformFont::CreateFromNameAndSize(const std::string& font_name,
                                                   int font_size) {
   return new PlatformFontPango(font_name, font_size);
 }
 
 }  // namespace gfx