Revert of Move JoinString to the base namespace

base/strings/string_util.h

 // Copyright 2013 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.
 //
 // This file defines utility functions for working with strings.
 
 #ifndef BASE_STRINGS_STRING_UTIL_H_
 #define BASE_STRINGS_STRING_UTIL_H_
 
 #include <ctype.h>
@@ skipping 473 matching lines @@
 // immediately write over this memory, but there is no other way to set the size
 // of the string, and not doing that will mean people who access |str| rather
 // than str.c_str() will get back a string of whatever size |str| had on entry
 // to this function (probably 0).
 BASE_EXPORT char* WriteInto(std::string* str, size_t length_with_null);
 BASE_EXPORT char16* WriteInto(base::string16* str, size_t length_with_null);
 #ifndef OS_WIN
 BASE_EXPORT wchar_t* WriteInto(std::wstring* str, size_t length_with_null);
 #endif
 
-// Does the opposite of SplitString().
-BASE_EXPORT std::string JoinString(const std::vector<std::string>& parts,
-                                   StringPiece separator);
-BASE_EXPORT string16 JoinString(const std::vector<string16>& parts,
-                                StringPiece16 separator);
-
 }  // namespace base
 
 #if defined(OS_WIN)
 #include "base/strings/string_util_win.h"
 #elif defined(OS_POSIX)
 #include "base/strings/string_util_posix.h"
 #else
 #error Define string operations appropriately for your platform
 #endif
 
+//-----------------------------------------------------------------------------
+
+// Does the opposite of SplitString().
+BASE_EXPORT base::string16 JoinString(const std::vector<base::string16>& parts,
+                                      base::char16 s);
+BASE_EXPORT std::string JoinString(
+    const std::vector<std::string>& parts, char s);
+
+// Join |parts| using |separator|.
+BASE_EXPORT std::string JoinString(
+    const std::vector<std::string>& parts,
+    const std::string& separator);
+BASE_EXPORT base::string16 JoinString(
+    const std::vector<base::string16>& parts,
+    const base::string16& separator);
+
 // Replace $1-$2-$3..$9 in the format string with |a|-|b|-|c|..|i| respectively.
 // Additionally, any number of consecutive '$' characters is replaced by that
 // number less one. Eg $$->$, $$$->$$, etc. The offsets parameter here can be
 // NULL. This only allows you to use up to nine replacements.
 BASE_EXPORT base::string16 ReplaceStringPlaceholders(
     const base::string16& format_string,
     const std::vector<base::string16>& subst,
     std::vector<size_t>* offsets);
 
 BASE_EXPORT std::string ReplaceStringPlaceholders(
     const base::StringPiece& format_string,
     const std::vector<std::string>& subst,
     std::vector<size_t>* offsets);
 
 // Single-string shortcut for ReplaceStringHolders. |offset| may be NULL.
 BASE_EXPORT base::string16 ReplaceStringPlaceholders(
     const base::string16& format_string,
     const base::string16& a,
     size_t* offset);
 
 #endif  // BASE_STRINGS_STRING_UTIL_H_