Fixes for re-enabling more MSVC level 4 warnings: misc edition #2

tools/gn/tokenizer.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/tokenizer.h"
 
 #include "base/logging.h"
 #include "tools/gn/input_file.h"
 
 namespace {
@@ skipping 116 matching lines @@
     if (type != Token::COMMENT)
       tokens_.push_back(Token(location, type, token_value));
   }
   if (err_->has_error())
     tokens_.clear();
   return tokens_;
 }
 
 // static
 size_t Tokenizer::ByteOffsetOfNthLine(const base::StringPiece& buf, int n) {
-  int cur_line = 1;
-  size_t cur_byte = 0;
-
-  DCHECK(n > 0);
+  DCHECK_GT(n, 0);
 
   if (n == 1)
     return 0;
 
+  int cur_line = 1;
+  size_t cur_byte = 0;
   while (cur_byte < buf.size()) {
     if (IsNewline(buf, cur_byte)) {
       cur_line++;
       if (cur_line == n)
         return cur_byte + 1;
     }
     cur_byte++;
   }
-  return -1;
+  return static_cast<size_t>(-1);
 }
 
 // static
 bool Tokenizer::IsNewline(const base::StringPiece& buffer, size_t offset) {
   DCHECK(offset < buffer.size());
   // We may need more logic here to handle different line ending styles.
   return buffer[offset] == '\n';
 }
 
 
@@ skipping 191 matching lines @@
   } else if (cur_char() == '/' && cur_ + 1 < input_.size() &&
       (input_[cur_ + 1] == '/' || input_[cur_ + 1] == '*')) {
     // Different types of comments.
     help = "Comments should start with # instead";
   } else {
     help = "I have no idea what this is.";
   }
 
   return Err(location, "Invalid token.", help);
 }