Revert "Enable Roboto by default for testing purpose."

ui/base/font_helper_chromeos.cc

 // Copyright 2014 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/base/font_helper_chromeos.h"
 
 #include "base/command_line.h"
 #include "ui/base/ui_base_switches.h"
 
 namespace ui {
 
 void ReplaceNotoSansWithRobotoIfEnabled(std::string* font_family) {
-  if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kDisableRobotoFontUI)) {
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableRobotoFontUI)) {
     static const char kNotoSansUI[] = "Noto Sans UI";
     static const size_t kNotoSansUILen = arraysize(kNotoSansUI) - 1;
     std::string::size_type noto_position = font_family->find(kNotoSansUI);
     if (noto_position != std::string::npos)
       font_family->replace(noto_position, kNotoSansUILen, "Roboto");
   }
 }
 
 }  // namespace ui