[Autofill] Credit Card Autofill Last Used Date Experiment

components/autofill/core/browser/credit_card.h

Index: components/autofill/core/browser/credit_card.h
diff --git a/components/autofill/core/browser/credit_card.h b/components/autofill/core/browser/credit_card.h
index d0a8a6eee7ee8b3b720d6e44035359baee0be127..c50dcb45e1164f3f0ea0ed6aa1bc0d2561ff9990 100644
--- a/components/autofill/core/browser/credit_card.h
+++ b/components/autofill/core/browser/credit_card.h
@@ -174,8 +174,14 @@ class CreditCard : public AutofillDataModel {
   // Sets |number_| to |number| and computes the appropriate card |type_|.
   void SetNumber(const base::string16& number);
 
-  // Logs the number of days since the credit card was last used and records its
-  // use.
+  // Returns the date(MM/DD) when the credit card was last used in autofill.
+  base::string16 LastUsedDateAsString(
+      bool show_time_detail,

[Jared Saul, 2017/01/18 18:43:44]

Based on outcome of my previous comment, should this be show_detailed_time_info
for consistency?

[jiahuiguo, 2017/01/18 22:18:13]

Done.

+      bool show_expiration_date,

[Jared Saul, 2017/01/18 18:43:44]

super nit: Likewise, show_expiration_date has come before
show_detailed_time_info everywhere else.  Can we swap these to keep the ordering
consistent?

[jiahuiguo, 2017/01/18 22:18:13]

Done.

+      const std::string& app_locale) const;
+
+  // Logs the number of days since the credit card was last used and records
+  // its use.
   void RecordAndLogUse();
 
   // Converts a string representation of a month (such as "February" or "feb."
@@ -185,6 +191,9 @@ class CreditCard : public AutofillDataModel {
                            const std::string& app_locale,
                            int* num);
 
+  base::string16 GetShortMonthLabel(int32_t zero_base_month_index,
+                                    const std::string& app_locale) const;
+
   // Returns whether the credit card is expired based on |current_time|.
   bool IsExpired(const base::Time& current_time) const;
 
@@ -213,6 +222,9 @@ class CreditCard : public AutofillDataModel {
   base::string16 Expiration4DigitYearAsString() const;
   base::string16 Expiration2DigitYearAsString() const;
 
+  // Padding month and day info to exactly 2 digits

[Jared Saul, 2017/01/18 18:43:44]

nit: Add period; looks like that's the norm around here

[jiahuiguo, 2017/01/18 22:18:13]

Done.

+  base::string16 PadTo2Digit(int32_t dateInfo) const;

[Mathieu, 2017/01/18 14:42:15]

can this be in the anonymous namespace in the cc file?

[Mathieu, 2017/01/18 14:42:15]

nit: date_info

[jiahuiguo, 2017/01/18 22:18:13]

Done.

[jiahuiguo, 2017/01/18 22:18:13]

Good point, done.

+
   // Sets |expiration_month_| to the integer conversion of |text| and returns
   // whether the operation was successful.
   bool SetExpirationMonthFromString(const base::string16& text,