Remove unused variable at credit_card_save_manager.h

strike_database_ variable seems not used anymore.

Bug: None
Change-Id: I984da6158b01b2d36b3e43da563b4ea912bec0ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2014213
Commit-Queue: Jared Saul <jsaul@google.com>
Reviewed-by: Jared Saul <jsaul@google.com>
Cr-Commit-Position: refs/heads/master@{#734093}

components/autofill/core/browser/payments/credit_card_save_manager.h

@@ -350,8 +350,6 @@ class CreditCardSaveManager {
   std::unique_ptr<LocalCardMigrationStrikeDatabase>
       local_card_migration_strike_database_;
 
-  std::unique_ptr<CreditCardSaveStrikeDatabase> strike_database_;
-
   // May be null.
   ObserverForTest* observer_for_testing_ = nullptr;