Move SetUseOverrideRedirectWindowByDefault() to //ui/base.

ui/base/platform_window_defaults.cc

+// Copyright 2017 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 "ui/base/platform_window_defaults.h"
+
+namespace ui {
+namespace {
+
+bool g_override_redirect = false;
+
+}  // namespace
+
+bool GetUseOverrideRedirectWindowByDefault() {
+  return g_override_redirect;
+}
+
+namespace test {
+
+void SetUseOverrideRedirectWindowByDefault(bool override_redirect) {
+  g_override_redirect = override_redirect;
+}
+
+}  // namespace test
+}  // namespace ui