Add Account method to update AccountActivityBySR.

r2/r2/models/account.py

@@ -589,6 +589,10 @@ class Account(Thing):
     def flair_enabled_in_sr(self, sr_id):
         return getattr(self, 'flair_%d_enabled' % sr_id, True)
 
+    def update_sr_activity(self, sr):
+        if not self._spam:
+            AccountActivityBySR.touch(self, sr)
+
 class FakeAccount(Account):
     _nodb = True
     pref_no_profanity = True