Adds a field trial to control Web API kill switches.

chrome/browser/permissions/permission_util.h

+// 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.
+
+#ifndef CHROME_BROWSER_PERMISSIONS_PERMISSION_UTIL_H_
+#define CHROME_BROWSER_PERMISSIONS_PERMISSION_UTIL_H_
+
+#include <string>
+
+#include "base/macros.h"
+#include "components/content_settings/core/common/content_settings_types.h"
+
+// A utility class for permissions.
+class PermissionUtil {
+ public:
+  // Returns the permission string for the given ContentSettingsType.
+  static std::string GetPermissionString(ContentSettingsType permission);
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(PermissionUtil);
+};
+
+#endif  // CHROME_BROWSER_PERMISSIONS_PERMISSION_UTIL_H_