Added --force-ui-direction flag for developers to force LTR or RTL.

base/i18n/base_i18n_switches.cc

+// 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.
+
+#include "base/i18n/base_i18n_switches.h"
+
+namespace switches {
+
+// Force the UI to a specific direction. Valid values are "ltr" (left-to-right)
+// and "rtl" (right-to-left).
+const char kForceUIDirection[]              = "force-ui-direction";
+
+const char kForceUIDirectionLTR[]           = "ltr";
+const char kForceUIDirectionRTL[]           = "rtl";
+
+}  // namespace switches