Prolong password histograms.

- PasswordManager.EmptyUsernames.CountInDatabase isn't useful anymore.
- PasswordManager.DeleteUndecryptableLoginsReturnValue is prolonged.

Fixed: 1153755
Change-Id: I487c2e7379c92348eeb4e1a705d367cc9b845bda
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2673523
Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Commit-Queue: Vasilii Sukhanov <vasilii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#851252}

components/password_manager/core/browser/login_database.cc

@@ -979,20 +979,6 @@ void LoginDatabase::ReportSyncingAccountStateMetrics(
                             4);
 }
 
-void LoginDatabase::ReportEmptyUsernamesMetrics() {
-  sql::Statement empty_usernames_statement(db_.GetCachedStatement(
-      SQL_FROM_HERE,
-      "SELECT COUNT(*) FROM logins "
-      "WHERE blacklisted_by_user=0 AND username_value=''"));
-  if (empty_usernames_statement.Step()) {
-    int empty_forms = empty_usernames_statement.ColumnInt(0);
-    base::UmaHistogramCounts100(
-        base::StrCat({kPasswordManager, GetMetricsSuffixForStore(),
-                      ".EmptyUsernames.CountInDatabase"}),
-        empty_forms);
-  }
-}
-
 void LoginDatabase::ReportLoginsWithSchemesMetrics() {
   sql::Statement logins_with_schemes_statement(db_.GetUniqueStatement(
       "SELECT signon_realm, origin_url, blacklisted_by_user FROM logins;"));
@@ -1127,7 +1113,6 @@ void LoginDatabase::ReportMetrics(const std::string& sync_username,
   ReportNumberOfAccountsMetrics(custom_passphrase_sync_enabled);
   ReportLoginsWithSchemesMetrics();
   ReportTimesPasswordUsedMetrics(custom_passphrase_sync_enabled);
-  ReportEmptyUsernamesMetrics();
   ReportInaccessiblePasswordsMetrics();
 
   // The remaining metrics are not recorded for the account store:

components/password_manager/core/browser/login_database_unittest.cc

@@ -1624,8 +1624,6 @@ TEST_F(LoginDatabaseTest, ReportMetricsTest) {
       "PasswordManager.TimesPasswordUsed.Overall.WithoutCustomPassphrase", 3,
       2);
 
-  histogram_tester.ExpectUniqueSample(
-      "PasswordManager.EmptyUsernames.CountInDatabase", 1, 1);
   histogram_tester.ExpectUniqueSample("PasswordManager.InaccessiblePasswords",
                                       0, 1);
 #if !defined(OS_IOS) && !defined(OS_ANDROID)
@@ -1745,8 +1743,6 @@ TEST_F(LoginDatabaseTest, ReportAccountStoreMetricsTest) {
       "WithoutCustomPassphrase",
       3, 2);
 
-  histogram_tester.ExpectUniqueSample(
-      "PasswordManager.AccountStore.EmptyUsernames.CountInDatabase", 1, 1);
   histogram_tester.ExpectUniqueSample(
       "PasswordManager.AccountStore.InaccessiblePasswords", 0, 1);
 }

tools/metrics/histograms/histograms_xml/password/histograms.xml

@@ -999,7 +999,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="PasswordManager.DeleteUndecryptableLoginsReturnValue"
-    enum="DeleteCorruptedPasswordsResult" expires_after="M89">
+    enum="DeleteCorruptedPasswordsResult" expires_after="M93">
   <owner>vasilii@chromium.org</owner>
   <owner>jdoerrie@chromium.org</owner>
   <summary>
@@ -1045,6 +1045,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="PasswordManager.EmptyUsernames.CountInDatabase" units="units"
     expires_after="M89">
+  <obsolete>
+    Obsolete since M90.
+  </obsolete>
   <owner>vasilii@chromium.org</owner>
   <owner>jdoerrie@chromium.org</owner>
   <summary>