[AF Paradise] Reset migration acceptance bit after a migration

If one migration request is finished and the user submits another
migration request in the same tab, the card would be automatically saved.

Reason: The member variable user_accepted_main_migration_dialog_ is not
correctly reset to false after a request is sent. So when next time the
risk data is loaded, a request would be direcly sent to server.

This is a bug for M71 code. Need to merge asap.

Bug: 897998
Change-Id: Ia77cdddc6d80550e0e23ff327f07a5c7279ba15f
Reviewed-on: https://chromium-review.googlesource.com/c/1333122
Commit-Queue: Siyu An <siyua@chromium.org>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607746}

components/autofill/core/browser/local_card_migration_manager.cc

@@ -245,6 +245,7 @@ void LocalCardMigrationManager::SendMigrateLocalCardsRequest() {
       migration_request_, migratable_credit_cards_,
       base::BindOnce(&LocalCardMigrationManager::OnDidMigrateLocalCards,
                      weak_ptr_factory_.GetWeakPtr()));
+  user_accepted_main_migration_dialog_ = false;
 }
 
 // Pops up a larger, modal dialog showing the local cards to be uploaded. Pass
@@ -252,7 +253,6 @@ void LocalCardMigrationManager::SendMigrateLocalCardsRequest() {
 // OnUserAcceptedMainMigrationDialog(). Can be called when user agrees to
 // migration on the intermediate dialog or directly from settings page.
 void LocalCardMigrationManager::ShowMainMigrationDialog() {
-  user_accepted_main_migration_dialog_ = false;
   AutofillMetrics::LogLocalCardMigrationPromptMetric(
       local_card_migration_origin_, AutofillMetrics::MAIN_DIALOG_SHOWN);
   // Pops up a larger, modal dialog showing the local cards to be uploaded.