Force --enable-webkit-text-subpixel-positioning for DSF > 1.0.

ui/gfx/font_render_params_linux.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/font_render_params.h"
 
 #include <fontconfig/fontconfig.h>
 
 #include "base/command_line.h"
 #include "base/containers/mru_cache.h"
@@ skipping 231 matching lines @@
   QueryFontconfig(actual_query, &params, family_out);
   if (!params.antialiasing) {
     // Cairo forces full hinting when antialiasing is disabled, since anything
     // less than that looks awful; do the same here. Requesting subpixel
     // rendering or positioning doesn't make sense either.
     params.hinting = FontRenderParams::HINTING_FULL;
     params.subpixel_rendering = FontRenderParams::SUBPIXEL_RENDERING_NONE;
     params.subpixel_positioning = false;
   } else {
     // Fontconfig doesn't support configuring subpixel positioning; check a
     // flag.

[Daniel Erat, 2015/03/20 23:51:50]

please delete this now-obsolete comment.

[stapelberg, 2015/03/31 18:11:57]

Done.

-    params.subpixel_positioning =
-        actual_query.for_web_contents
-            ? base::CommandLine::ForCurrentProcess()->HasSwitch(
-                  switches::kEnableWebkitTextSubpixelPositioning)

[Daniel Erat, 2015/03/20 23:51:50]

this looks like it was the only place where this flag was used, so please remove
the other three references to the constant from chrome as well.

[stapelberg, 2015/03/31 18:11:57]

Done.

-            : actual_query.device_scale_factor > 1.0f;
+    params.subpixel_positioning = actual_query.device_scale_factor > 1.0f;
 
     // To enable subpixel positioning, we need to disable hinting.
     if (params.subpixel_positioning)
       params.hinting = FontRenderParams::HINTING_NONE;
   }
 
   // Use the first family from the list if Fontconfig didn't suggest a family.
   if (family_out && family_out->empty() && !actual_query.families.empty())
     *family_out = actual_query.families[0];
 
@@ skipping 18 matching lines @@
 float GetFontRenderParamsDeviceScaleFactor() {
   return device_scale_factor_for_internal_display;
 }
 
 void SetFontRenderParamsDeviceScaleFactor(float device_scale_factor) {
   device_scale_factor_for_internal_display = device_scale_factor;
 }
 #endif
 
 }  // namespace gfx