Pass Manifest JSON paser error line and column number to console.

base/json/json_reader.h

 // Copyright (c) 2012 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.
 //
 // A JSON parser.  Converts strings of JSON into a Value object (see
 // base/values.h).
 // http://www.ietf.org/rfc/rfc4627.txt?number=4627
 //
 // Known limitations/deviations from the RFC:
 // - Only knows how to parse ints within the range of a signed 32 bit int and
@@ skipping 89 matching lines @@
   // returns NULL.
   static scoped_ptr<Value> Read(const StringPiece& json, int options);
 
   // Reads and parses |json| like Read(). |error_code_out| and |error_msg_out|
   // are optional. If specified and NULL is returned, they will be populated
   // an error code and a formatted error message (including error location if
   // appropriate). Otherwise, they will be unmodified.
   static scoped_ptr<Value> ReadAndReturnError(const StringPiece& json,
                                               int options,  // JSONParserOptions
                                               int* error_code_out,
-                                              std::string* error_msg_out);
+                                              std::string* error_msg_out,
+                                              int* error_line_out = nullptr,
+                                              int* error_column_out = nullptr);

[Nico, 2016/01/13 20:50:39]

That'd also help here...

 
   // Converts a JSON parse error code into a human readable message.
   // Returns an empty string if error_code is JSON_NO_ERROR.
   static std::string ErrorCodeToString(JsonParseError error_code);
 
   // Parses an input string into a Value that is owned by the caller.
   scoped_ptr<Value> ReadToValue(const std::string& json);
 
   // Returns the error code if the last call to ReadToValue() failed.
   // Returns JSON_NO_ERROR otherwise.
   JsonParseError error_code() const;
 
   // Converts error_code_ to a human-readable string, including line and column
   // numbers if appropriate.
   std::string GetErrorMessage() const;
 
  private:
   scoped_ptr<internal::JSONParser> parser_;
 };
 
 }  // namespace base
 
 #endif  // BASE_JSON_JSON_READER_H_