base: Move SplitStringUsingSubstr functions from string_util.h to string_split.h

base/string_split.h

 // Copyright (c) 2010 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 BASE_STRING_SPLIT_H_
 #define BASE_STRING_SPLIT_H_
 #pragma once
 
 #include <string>
 #include <utility>
 #include <vector>
 
+#include "base/string16.h"
+
 namespace base {
 
 bool SplitStringIntoKeyValues(
     const std::string& line,
     char key_value_delimiter,
     std::string* key, std::vector<std::string>* values);
 
 bool SplitStringIntoKeyValuePairs(
     const std::string& line,
     char key_value_delimiter,
     char key_value_pair_delimiter,
     std::vector<std::pair<std::string, std::string> >* kv_pairs);
 
+// The same as SplitString, but use a substring delimiter instead of a char.
+void SplitStringUsingSubstr(const string16& str,
+                            const string16& s,
+                            std::vector<string16>* r);
+void SplitStringUsingSubstr(const std::string& str,
+                            const std::string& s,
+                            std::vector<std::string>* r);
+
 }  // namespace base
 
 #endif  // BASE_STRING_SPLIT_H