Updates subpixel positioning and hinting when DSF is changed

ui/gfx/platform_font_mac.mm

 // 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_mac.h"
 
 #include <Cocoa/Cocoa.h>
 
 #include "base/basictypes.h"
 #include "base/mac/scoped_nsobject.h"
@@ skipping 156 matching lines @@
   height_ = SkScalarCeilToInt([layout_manager defaultLineHeightForFont:font]);
   ascent_ = SkScalarCeilToInt([font ascender]);
   cap_height_ = SkScalarCeilToInt([font capHeight]);
   average_width_ =
       NSWidth([font boundingRectForGlyph:[font glyphWithName:@"x"]]);
 
   FontRenderParamsQuery query(false);
   query.families.push_back(font_name_);
   query.pixel_size = font_size_;
   query.style = font_style_;
-  render_params_ = gfx::GetFontRenderParams(query, NULL);
+  render_params_ = gfx::GetSystemFontRenderParams(query, NULL);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // PlatformFont, public:
 
 // static
 PlatformFont* PlatformFont::CreateDefault() {
   return new PlatformFontMac;
 }
 
 // static
 PlatformFont* PlatformFont::CreateFromNativeFont(NativeFont native_font) {
   return new PlatformFontMac(native_font);
 }
 
 // static
 PlatformFont* PlatformFont::CreateFromNameAndSize(const std::string& font_name,
                                                   int font_size) {
   return new PlatformFontMac(font_name, font_size);
 }
 
 }  // namespace gfx