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

rlz/win/lib/machine_deal.cc

Index: rlz/win/lib/machine_deal.cc
diff --git a/rlz/win/lib/machine_deal.cc b/rlz/win/lib/machine_deal.cc
index afb935fe61631343d12ddd816132c4eb2e4e2b45..5b5d007885f41b8b87b7628b321e54ba128bf1da 100644
--- a/rlz/win/lib/machine_deal.cc
+++ b/rlz/win/lib/machine_deal.cc
@@ -57,7 +57,7 @@ bool IsGoodDccChar(char ch) {
 // reasonable size. It also assumes that normalized_dcc is at least
 // kMaxDccLength+1 long.
 void NormalizeDcc(const char* raw_dcc, char* normalized_dcc) {
-  int index = 0;
+  size_t index = 0;
   for (; raw_dcc[index] != 0 && index < rlz_lib::kMaxDccLength; ++index) {
     char current = raw_dcc[index];
     if (IsGoodDccChar(current)) {