Convert --enable-md-history to a feature flag.

chrome/browser/browser_about_handler.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 "chrome/browser/browser_about_handler.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_util.h"
 #include "base/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "chrome/browser/lifetime/application_lifetime.h"
 #include "chrome/browser/ui/browser_dialogs.h"
+#include "chrome/common/chrome_features.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
 #include "components/url_formatter/url_fixer.h"
 
 bool FixupBrowserAboutURL(GURL* url,
                           content::BrowserContext* browser_context) {
   // Ensure that any cleanup done by FixupURL happens before the rewriting
   // phase that determines the virtual URL, by including it in an initial
   // URLHandler.  This prevents minor changes from producing a virtual URL,
   // which could lead to a URL spoof.
@@ skipping 39 matching lines @@
     }
   // Redirect chrome://settings/extensions (legacy URL).
   } else if (host == chrome::kChromeUISettingsHost &&
       url->path() == std::string("/") + chrome::kExtensionsSubPage) {
     host = chrome::kChromeUIUberHost;
     path = chrome::kChromeUIExtensionsHost;
   // Redirect chrome://history.
   } else if (host == chrome::kChromeUIHistoryHost) {
     // Material design history is handled on the top-level chrome://history
     // host.
-    if (::switches::MdHistoryEnabled()) {
+    if (base::FeatureList::IsEnabled(features::kMaterialDesignHistoryFeature)) {
       host = chrome::kChromeUIHistoryHost;
       path = url->path();
     } else {
 #if defined(OS_ANDROID)
       // On Android, redirect directly to chrome://history-frame since
       // uber page is unsupported.
       host = chrome::kChromeUIHistoryFrameHost;
 #else
       host = chrome::kChromeUIUberHost;
       path = chrome::kChromeUIHistoryHost + url->path();
@@ skipping 39 matching lines @@
         FROM_HERE, base::Bind(&chrome::AttemptRestart));
     return true;
   } else if (base::LowerCaseEqualsASCII(spec, chrome::kChromeUIQuitURL)) {
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE, base::Bind(&chrome::AttemptExit));
     return true;
   }
 
   return false;
 }