Refactorise the policy_path_parser framework

chrome/browser/policy/policy_path_parser.h

 // 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.
 
 #ifndef CHROME_BROWSER_POLICY_POLICY_PATH_PARSER_H_
 #define CHROME_BROWSER_POLICY_POLICY_PATH_PARSER_H_
 
 #include <string>
 
+#include "base/bind.h"
 #include "base/files/file_path.h"
 
 namespace policy {
 
 namespace path_parser {
 
+namespace internal {
+
+typedef bool (*GetValueFuncPtr)(base::FilePath::StringType*);
+
+struct VariableNameAndValueCallback {
+  const base::FilePath::CharType* name;
+  const GetValueFuncPtr value_func_ptr;
+};
+
+// Different set of variables are supported in each platform (see below). Hence
+// this table is filled in with different elements in each platform.
+extern const VariableNameAndValueCallback kVariableNameAndValueCallbacks[];
+
+// Since the number of elements in the table could vary for each platform, this
+// variable is used to keep track of it.
+extern const int kNoOfVariables;
+}
+
 // This function is used to expand the variables in policy strings that
 // represent paths. The set of supported variables differs between platforms
 // but generally covers most standard locations that might be needed in the
 // existing used cases.
 // All platforms:
 //   ${user_name}       - The user that is running Chrome (respects suids).
 //                        (example : "johndoe")
 //   ${machine_name}    - The machine name possibly with domain (example :
 //                        "johnny.cg1.cooldomain.org")
 // Windows only:
@@ skipping 32 matching lines @@
 // this function should be used to verify no policy is specified whenever the
 // profile path is not read from the PathService which already takes this into
 // account.
 void CheckUserDataDirPolicy(base::FilePath* user_data_dir);
 
 }  // namespace path_parser
 
 }  // namespace policy
 
 #endif  // CHROME_BROWSER_POLICY_POLICY_PATH_PARSER_H_