linux: Pass subpixel positioning setting to WebKit.

content/public/common/renderer_preferences.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.
 //
 // A struct for managing browser's settings that apply to the renderer or its
 // webview.  These differ from WebPreferences since they apply to Chromium's
 // glue layer rather than applying to just WebKit.
 //
 // Adding new values to this class probably involves updating
 // common/view_messages.h, browser/browser.cc, etc.
@@ skipping 36 matching lines @@
   bool should_antialias_text;
 
   // The level of hinting to use when rendering text.
   // Currently only used by Linux.
   RendererPreferencesHintingEnum hinting;
 
   // The type of subpixel rendering to use for text.
   // Currently only used by Linux.
   RendererPreferencesSubpixelRenderingEnum subpixel_rendering;
 
+  // Whether subpixel positioning should be used, permitting fractional X
+  // positions for glyphs.  Currently only used by Linux.
+  bool use_subpixel_positioning;
+
   // The color of the focus ring. Currently only used on Linux.
   SkColor focus_ring_color;
 
   // The color of different parts of the scrollbar. Currently only used on
   // Linux.
   SkColor thumb_active_color;
   SkColor thumb_inactive_color;
   SkColor track_color;
 
   // The colors used in selection text. Currently only used on Linux.
@@ skipping 16 matching lines @@
   // Set to false to not send referrers.
   bool enable_referrers;
 
   // Default page zoom level.
   double default_zoom_level;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_COMMON_RENDERER_PREFERENCES_H_