Add a path parsing policy handler for the RoamingProfileLocation policy.

chrome/browser/policy/local_sync_policy_handler.cc

Index: chrome/browser/policy/local_sync_policy_handler.cc
diff --git a/chrome/browser/policy/local_sync_policy_handler.cc b/chrome/browser/policy/local_sync_policy_handler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..88758efee685b1adfae16ef0d3745afcaa76030d
--- /dev/null
+++ b/chrome/browser/policy/local_sync_policy_handler.cc
@@ -0,0 +1,36 @@
+// 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 "chrome/browser/policy/local_sync_policy_handler.h"
+
+#include "base/files/file_path.h"
+#include "base/memory/ptr_util.h"
+#include "base/values.h"
+#include "chrome/browser/policy/policy_path_parser.h"
+#include "components/policy/core/common/policy_map.h"
+#include "components/policy/policy_constants.h"
+#include "components/prefs/pref_value_map.h"
+#include "components/sync/base/pref_names.h"
+
+namespace policy {
+
+LocalSyncPolicyHandler::LocalSyncPolicyHandler()
+    : TypeCheckingPolicyHandler(key::kRoamingProfileLocation,
+                                base::Value::Type::STRING) {}
+
+LocalSyncPolicyHandler::~LocalSyncPolicyHandler() {}
+
+void LocalSyncPolicyHandler::ApplyPolicySettings(const PolicyMap& policies,
+                                                 PrefValueMap* prefs) {
+  const base::Value* value = policies.GetValue(policy_name());
+  base::FilePath::StringType string_value;
+  if (value && value->GetAsString(&string_value)) {
+    base::FilePath::StringType expanded_value =
+        policy::path_parser::ExpandPathVariables(string_value);
+    prefs->SetValue(syncer::prefs::kLocalSyncBackendDir,
+                    base::MakeUnique<base::Value>(expanded_value));
+  }
+}
+
+}  // namespace policy