Replace base::str[n]casecmp with helper functions.

net/tools/balsa/string_piece_utils.h

Index: net/tools/balsa/string_piece_utils.h
diff --git a/net/tools/balsa/string_piece_utils.h b/net/tools/balsa/string_piece_utils.h
index 7d8a1aaaee28733cd8afe70374822a91c4e3b9f8..6d8967a014219416c98ec37b75e1401d5de6fcd9 100644
--- a/net/tools/balsa/string_piece_utils.h
+++ b/net/tools/balsa/string_piece_utils.h
@@ -65,31 +65,10 @@ struct StringPieceCaseHash {
 };
 #endif  // COMPILER_MSVC
 
-struct StringPieceUtils {
-  // ASCII case-insensitive equality.
-  static bool EqualIgnoreCase(const base::StringPiece& piece1,
-                              const base::StringPiece& piece2) {
-    base::StringPiece::const_iterator p1i = piece1.begin();
-    base::StringPiece::const_iterator p2i = piece2.begin();
-    if (piece1.empty() && piece2.empty()) {
-      return true;
-    } else if (piece1.size() != piece2.size()) {
-      return false;
-    }
-    while (p1i != piece1.end() && p2i != piece2.end()) {
-      if (base::ToLowerASCII(*p1i) != base::ToLowerASCII(*p2i))
-        return false;
-      ++p1i;
-      ++p2i;
-    }
-    return true;
-  }
-};
-
 struct StringPieceCaseEqual {
   bool operator()(const base::StringPiece& piece1,
                   const base::StringPiece& piece2) const {
-    return StringPieceUtils::EqualIgnoreCase(piece1, piece2);
+    return base::EqualsCaseInsensitiveASCII(piece1, piece2);
   }
 };