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

chrome/test/data/webui/md_history/md_history_browsertest.js

 // Copyright 2015 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.
 
 /**
  * @fileoverview Test suite for the Material Design history page.
  */
 
 var ROOT_PATH = '../../../../../';
 
 GEN_INCLUDE(
     [ROOT_PATH + 'chrome/test/data/webui/polymer_browser_test_base.js']);
 GEN('#include "base/command_line.h"');
 GEN('#include "chrome/test/data/webui/history_ui_browsertest.h"');
 
 function MaterialHistoryBrowserTest() {}
 
 MaterialHistoryBrowserTest.prototype = {
   __proto__: PolymerTest.prototype,
 
   browsePreload: 'chrome://history',
 
-  commandLineSwitches: [{switchName: 'enable-md-history'}],
+  commandLineSwitches: [{switchName: 'enable-features',
+                         switchValue: 'MaterialDesignHistory'}],
 
   /** @override */
   runAccessibilityChecks: false,
 
   extraLibraries: PolymerTest.getLibraries(ROOT_PATH).concat([
     'test_util.js',
     'history_list_test.js',
     'history_item_test.js',
     'history_overflow_menu_test.js',
     'history_supervised_user_test.js',
@@ skipping 31 matching lines @@
   testGenPreamble: function() {
     GEN('  SetDeleteAllowed(false);');
   }
 };
 
 TEST_F('MaterialHistoryDeletionDisabledTest', 'HistorySupervisedUserTest',
     function() {
   md_history.history_supervised_user_test.registerTests();
   mocha.run();
 });