gn: attach comments to parse tree

tools/gn/location.cc

 // Copyright (c) 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.
 
 #include "tools/gn/location.h"
 
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "tools/gn/input_file.h"
 
 Location::Location()
     : file_(NULL),
       line_number_(-1),
       char_offset_(-1) {
 }
 
-Location::Location(const InputFile* file, int line_number, int char_offset)
+Location::Location(const InputFile* file,
+                   int line_number,
+                   int char_offset,
+                   int byte)
     : file_(file),
       line_number_(line_number),
-      char_offset_(char_offset) {
+      char_offset_(char_offset),
+      byte_(byte) {
 }
 
 bool Location::operator==(const Location& other) const {
   return other.file_ == file_ &&
          other.line_number_ == line_number_ &&
          other.char_offset_ == char_offset_;
 }
 
 bool Location::operator!=(const Location& other) const {
   return !operator==(other);
@@ skipping 33 matching lines @@
       end_(end) {
   DCHECK(begin_.file() == end_.file());
 }
 
 LocationRange LocationRange::Union(const LocationRange& other) const {
   DCHECK(begin_.file() == other.begin_.file());
   return LocationRange(
       begin_ < other.begin_ ? begin_ : other.begin_,
       end_ < other.end_ ? other.end_ : end_);
 }