Fix crash in save card banner mediator due to null save card delegate.

This CL adds a check for null AutofillSaveCardInfoBarDelegateIOS
in SaveCardInfoBarBannerOverlayMediator.dismissInfobarBannerFor-
UserInteraction. Fixes immediate crash, see crbug.com/409220427

Bug: 409220427
Change-Id: I207bb4d43ca4a44bd1793150913387e851e8cfd7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6443738
Reviewed-by: Chris Lu <thegreenfrog@chromium.org>
Commit-Queue: Kavita Soni <kavitasoni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1445625}

ios/chrome/browser/overlays/ui_bundled/infobar_banner/save_card/save_card_infobar_banner_overlay_mediator.mm

@@ -78,21 +78,22 @@
 - (void)dismissInfobarBannerForUserInteraction:(BOOL)userInitiated {
   autofill::AutofillSaveCardInfoBarDelegateIOS* delegate =
       self.saveCardDelegate;
-
-  if (!userInitiated) {
-    // Banner is dismissed without user interaction when it times out.
-    delegate->LogSaveCreditCardInfoBarResultMetric(
-        autofill::autofill_metrics::SaveCreditCardPromptResultIOS::KTimedOut,
-        autofill::autofill_metrics::SaveCreditCardPromptOverlayType::kBanner);
-  } else if (userInitiated && !_bannerButtonWasPressed) {
-    // Banner is dismissed with user interaction by swiping it up or by tapping
-    // its button. To distinguish swipe-up dismissal, the method checks if the
-    // button was pressed.
-    delegate->LogSaveCreditCardInfoBarResultMetric(
-        autofill::autofill_metrics::SaveCreditCardPromptResultIOS::kSwiped,
-        autofill::autofill_metrics::SaveCreditCardPromptOverlayType::kBanner);
+  // Delegate may be null due to crbug.com/409220427
+  if (delegate) {
+    if (!userInitiated) {
+      // Banner is dismissed without user interaction when it times out.
+      delegate->LogSaveCreditCardInfoBarResultMetric(
+          autofill::autofill_metrics::SaveCreditCardPromptResultIOS::KTimedOut,
+          autofill::autofill_metrics::SaveCreditCardPromptOverlayType::kBanner);
+    } else if (userInitiated && !_bannerButtonWasPressed) {
+      // Banner is dismissed with user interaction by swiping it up or by
+      // tapping its button. To distinguish swipe-up dismissal, the method
+      // checks if the button was pressed.
+      delegate->LogSaveCreditCardInfoBarResultMetric(
+          autofill::autofill_metrics::SaveCreditCardPromptResultIOS::kSwiped,
+          autofill::autofill_metrics::SaveCreditCardPromptOverlayType::kBanner);
+    }
   }
-
   [super dismissInfobarBannerForUserInteraction:userInitiated];
 }