Add a policy to re-enable deprecated web platform features.

chrome/browser/policy/policy_browsertest.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 <algorithm>
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 2957 matching lines @@
                POLICY_SCOPE_USER, whitelist.DeepCopy(), NULL);
   UpdateProviderPolicy(policies);
 
   PrefService* prefs = browser()->profile()->GetPrefs();
   EXPECT_TRUE(extensions::NativeMessageProcessHost::IsHostAllowed(
       prefs, "host.name"));
   EXPECT_FALSE(extensions::NativeMessageProcessHost::IsHostAllowed(
       prefs, "other.host.name"));
 }
 
+IN_PROC_BROWSER_TEST_F(PolicyTest,
+                       EnableDeprecatedWebPlatformFeatures_ShowModalDialog) {
+  base::ListValue enabled_features;
+  enabled_features.Append(base::Value::CreateStringValue("ShowModalDialog"));
+  PolicyMap policies;
+  policies.Set(key::kEnableDeprecatedWebPlatformFeatures,
+               POLICY_LEVEL_MANDATORY,
+               POLICY_SCOPE_USER,
+               enabled_features.DeepCopy(),
+               NULL);
+  UpdateProviderPolicy(policies);
+
+  ui_test_utils::NavigateToURL(browser(), GURL(content::kAboutBlankURL));
+  bool result = false;
+  EXPECT_TRUE(content::ExecuteScriptAndExtractBool(
+      browser()->tab_strip_model()->GetActiveWebContents(),
+      "domAutomationController.send(window.showModalDialog !== undefined);",
+      &result));
+  EXPECT_TRUE(result);
+}
+
 #endif  // !defined(CHROME_OS)
 
 }  // namespace policy