[Autofill] Autofill incorrectly fills credit card expiration year in 2-digit fields.

components/autofill/core/browser/credit_card_field.h

Index: components/autofill/core/browser/credit_card_field.h
diff --git a/components/autofill/core/browser/credit_card_field.h b/components/autofill/core/browser/credit_card_field.h
index bf45e7ee6efb0194481158448104546b07e9ff85..64fa4edc941f65057427305c90a025d65b0191bb 100644
--- a/components/autofill/core/browser/credit_card_field.h
+++ b/components/autofill/core/browser/credit_card_field.h
@@ -31,12 +31,17 @@ class CreditCardField : public FormField {
 
   CreditCardField();
 
+  // For the combined expiration field we return |exp_year_type_|; otherwise if
+  // |expiration_year_| is having year with |max_length| of 2-digits we return
+  // |CREDIT_CARD_EXP_2_DIGIT_YEAR|; otherwise |CREDIT_CARD_EXP_4_DIGIT_YEAR|.
+  ServerFieldType GetExpirationYearType() const;
+
   const AutofillField* cardholder_;  // Optional.
 
   // Occasionally pages have separate fields for the cardholder's first and
-  // last names; for such pages cardholder_ holds the first name field and
+  // last names; for such pages |cardholder_| holds the first name field and
   // we store the last name field here.
-  // (We could store an embedded NameField object here, but we don't do so
+  // (We could store an embedded |NameField| object here, but we don't do so
   // because the text patterns for matching a cardholder name are different
   // than for ordinary names, and because cardholder names never have titles,
   // middle names or suffixes.)
@@ -55,9 +60,10 @@ class CreditCardField : public FormField {
   const AutofillField* expiration_year_;
   const AutofillField* expiration_date_;
 
-  // True if the year is detected to be a 2-digit year; otherwise, we assume
-  // a 4-digit year.
-  bool is_two_digit_year_;
+  // For combined expiration field having year as 2-digits we store here
+  // |CREDIT_CARD_EXP_DATE_2_DIGIT_YEAR|; otherwise we store
+  // |CREDIT_CARD_EXP_DATE_4_DIGIT_YEAR|.
+  ServerFieldType exp_year_type_;
 
   DISALLOW_COPY_AND_ASSIGN(CreditCardField);
 };