More or less implement RenderTextHarfBuzz

ui/gfx/switches.cc

 // Copyright 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/switches.h"
 
 namespace switches {
 
 // Let text glyphs have X-positions that aren't snapped to the pixel grid in
 // the browser UI.
 const char kEnableBrowserTextSubpixelPositioning[] =
     "enable-browser-text-subpixel-positioning";
 
+// Uses the HarfBuzz port of RenderText on all platforms.
+const char kEnableHarfBuzzRenderText[] =
+    "enable-harfbuzz-rendertext";
+
 // Enable text glyphs to have X-positions that aren't snapped to the pixel grid
 // in webkit renderers.
 const char kEnableWebkitTextSubpixelPositioning[] =
     "enable-webkit-text-subpixel-positioning";
 
 // Overrides the device scale factor for the browser UI and the contents.
 const char kForceDeviceScaleFactor[] = "force-device-scale-factor";
 
 // Enables/Disables High DPI support (windows)
 const char kHighDPISupport[] = "high-dpi-support";
 
 }  // namespace switches