tools/gn: Change auto to not deduce raw pointers.

tools/gn/parse_tree_unittest.cc

 // Copyright 2014 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/parse_tree.h"
 
 #include <stdint.h>
 #include <utility>
 
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 207 matching lines @@
 }
 
 TEST(ParseTree, Integers) {
   static const char* const kGood[] = {
       "0",
       "10",
       "-54321",
       "9223372036854775807",   // INT64_MAX
       "-9223372036854775808",  // INT64_MIN
   };
-  for (auto s : kGood) {
+  for (auto* s : kGood) {
     TestParseInput input(std::string("x = ") + s);
     EXPECT_FALSE(input.has_error());
 
     TestWithScope setup;
     Err err;
     input.parsed()->Execute(setup.scope(), &err);
     EXPECT_FALSE(err.has_error());
   }
 
   static const char* const kBad[] = {
       "-0",
       "010",
       "-010",
       "9223372036854775808",   // INT64_MAX + 1
       "-9223372036854775809",  // INT64_MIN - 1
   };
-  for (auto s : kBad) {
+  for (auto* s : kBad) {
     TestParseInput input(std::string("x = ") + s);
     EXPECT_FALSE(input.has_error());
 
     TestWithScope setup;
     Err err;
     input.parsed()->Execute(setup.scope(), &err);
     EXPECT_TRUE(err.has_error());
   }
 }