IsStringUTF8 unittest and enforcing UTF-8 in JSON deserialization

base/string_util.h

Index: base/string_util.h
===================================================================
--- base/string_util.h	(revision 2506)
+++ base/string_util.h	(working copy)
@@ -222,8 +222,8 @@
 // first case) or characters that use only 8-bits and whose 8-bit
 // representation looks like a UTF-8 string (the second case).
 bool IsString8Bit(const std::wstring& str);
-bool IsStringUTF8(const char* str);
-bool IsStringWideUTF8(const wchar_t* str);
+bool IsStringUTF8(const std::string& str);
+bool IsStringWideUTF8(const std::wstring& str);
 bool IsStringASCII(const std::wstring& str);
 bool IsStringASCII(const std::string& str);