clang/win: Let some chromium_code targets build with -Wextra.

base/files/file_util_unittest.cc

 // 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.
 
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #include <shlobj.h>
@@ skipping 335 matching lines @@
   // Without making the path a bit shorter, CreateDirectory() fails.
   // the resulting path is still long enough to hit the failing case in
   // NormalizePath().
   const int kCreateDirLimit = 4;
   target_length -= kCreateDirLimit;
   FilePath::StringType long_name_str = FPL("long_name_");
   long_name_str.resize(target_length, '_');
 
   FilePath long_name = sub_a.Append(FilePath(long_name_str));
   FilePath deep_file = long_name.Append(sub_long_rel).Append(deep_txt);
-  ASSERT_EQ(MAX_PATH - kCreateDirLimit, deep_file.value().length());
+  ASSERT_EQ(static_cast<size_t>(MAX_PATH - kCreateDirLimit),
+            deep_file.value().length());
 
   FilePath sub_long = deep_file.DirName();
   ASSERT_TRUE(CreateDirectory(sub_long));
   CreateTextFile(deep_file, bogus_content);
 
   FilePath base_b = temp_dir_.path().Append(FPL("base_b"));
   ASSERT_TRUE(CreateDirectory(base_b));
 
   FilePath to_sub_a = base_b.Append(FPL("to_sub_a"));
   ASSERT_TRUE(CreateDirectory(to_sub_a));
@@ skipping 2151 matching lines @@
   // Trying to close it should crash. This is important for security.
   EXPECT_DEATH(CloseWithScopedFD(fds[1]), "");
 #endif
 }
 
 #endif  // defined(OS_POSIX)
 
 }  // namespace
 
 }  // namespace base