Add JSON-specific escaping, which has different rules from JS escaping.

base/string_util.cc

Index: base/string_util.cc
===================================================================
--- base/string_util.cc	(revision 16481)
+++ base/string_util.cc	(working copy)
@@ -37,35 +37,6 @@
   const string16 s16;
 };
 
-// Hack to convert any char-like type to its unsigned counterpart.
-// For example, it will convert char, signed char and unsigned char to unsigned
-// char.
-template<typename T>
-struct ToUnsigned {
-  typedef T Unsigned;
-};
-
-template<>
-struct ToUnsigned<char> {
-  typedef unsigned char Unsigned;
-};
-template<>
-struct ToUnsigned<signed char> {
-  typedef unsigned char Unsigned;
-};
-template<>
-struct ToUnsigned<wchar_t> {
-#if defined(WCHAR_T_IS_UTF16)
-  typedef unsigned short Unsigned;
-#elif defined(WCHAR_T_IS_UTF32)
-  typedef uint32 Unsigned;
-#endif
-};
-template<>
-struct ToUnsigned<short> {
-  typedef unsigned short Unsigned;
-};
-
 // Used by ReplaceStringPlaceholders to track the position in the string of
 // replaced parameters.
 struct ReplacementOffset {