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

base/file_version_info_win.cc

Index: base/file_version_info_win.cc
diff --git a/base/file_version_info_win.cc b/base/file_version_info_win.cc
index ca3e4b1fa3af6ac0d8511be8dac44675ad260c2a..a7dc216ce7bc7f3111d32076f7ca8a28ba04d80e 100644
--- a/base/file_version_info_win.cc
+++ b/base/file_version_info_win.cc
@@ -149,7 +149,7 @@ bool FileVersionInfoWin::is_official_build() {
 bool FileVersionInfoWin::GetValue(const wchar_t* name,
                                   std::wstring* value_str) {
   WORD lang_codepage[8];
-  int i = 0;
+  size_t i = 0;
   // Use the language and codepage from the DLL.
   lang_codepage[i++] = language_;
   lang_codepage[i++] = code_page_;