Revert of Stop doing unnecessary UTF-8 to UTF-16 conversions in JSONWriter.

base/json/string_escape.h

Index: base/json/string_escape.h
diff --git a/base/json/string_escape.h b/base/json/string_escape.h
index b66b7e54532e4f195847b8ad817f93e20418be89..0f16f59d4fd8bc3d427b751385272b08f175b212 100644
--- a/base/json/string_escape.h
+++ b/base/json/string_escape.h
@@ -1,8 +1,8 @@
 // Copyright (c) 2011 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 escaping strings suitable for JSON.
+//
+// This file defines utility functions for escaping strings.
 
 #ifndef BASE_JSON_STRING_ESCAPE_H_
 #define BASE_JSON_STRING_ESCAPE_H_
@@ -14,46 +14,24 @@
 
 namespace base {
 
-// Appends to |dest| an escaped version of |str|. Valid UTF-8 code units will
-// pass through from the input to the output. Invalid code units will be
-// replaced with the U+FFFD replacement character. This function returns true
-// if no replacement was necessary and false if there was a lossy replacement.
-// On return, |dest| will contain a valid UTF-8 JSON string.
-//
-// Non-printing control characters will be escaped as \uXXXX sequences for
-// readability.
-//
-// If |put_in_quotes| is true, then a leading and trailing double-quote mark
-// will be appended to |dest| as well.
-BASE_EXPORT bool EscapeJSONString(const StringPiece& str,
-                                  bool put_in_quotes,
-                                  std::string* dest);
+// Escape |str| appropriately for a JSON string literal, _appending_ the
+// result to |dst|. This will create unicode escape sequences (\uXXXX).
+// If |put_in_quotes| is true, the result will be surrounded in double quotes.
+// The outputted literal, when interpreted by the browser, should result in a
+// javascript string that is identical and the same length as the input |str|.
+BASE_EXPORT void JsonDoubleQuote(const StringPiece& str,
+                                 bool put_in_quotes,
+                                 std::string* dst);
 
-// Performs a similar function to the UTF-8 StringPiece version above,
-// converting UTF-16 code units to UTF-8 code units and escaping non-printing
-// control characters. On return, |dest| will contain a valid UTF-8 JSON string.
-BASE_EXPORT bool EscapeJSONString(const StringPiece16& str,
-                                  bool put_in_quotes,
-                                  std::string* dest);
+// Same as above, but always returns the result double quoted.
+BASE_EXPORT std::string GetDoubleQuotedJson(const StringPiece& str);
 
-// Helper functions that wrap the above two functions but return the value
-// instead of appending. |put_in_quotes| is always true.
-BASE_EXPORT std::string GetQuotedJSONString(const StringPiece& str);
-BASE_EXPORT std::string GetQuotedJSONString(const StringPiece16& str);
+BASE_EXPORT void JsonDoubleQuote(const StringPiece16& str,
+                                 bool put_in_quotes,
+                                 std::string* dst);
 
-// Given an arbitrary byte string |str|, this will escape all non-ASCII bytes
-// as \uXXXX escape sequences. This function is *NOT* meant to be used with
-// Unicode strings and does not validate |str| as one.
-//
-// CAVEAT CALLER: The output of this function may not be valid JSON, since
-// JSON requires escape sequences to be valid UTF-16 code units. This output
-// will be mangled if passed to to the base::JSONReader, since the reader will
-// interpret it as UTF-16 and convert it to UTF-8.
-//
-// The output of this function takes the *appearance* of JSON but is not in
-// fact valid according to RFC 4627.
-BASE_EXPORT std::string EscapeBytesAsInvalidJSONString(const StringPiece& str,
-                                                       bool put_in_quotes);
+// Same as above, but always returns the result double quoted.
+BASE_EXPORT std::string GetDoubleQuotedJson(const StringPiece16& str);
 
 }  // namespace base