Return •••••••• for password autofill suggestions

Change-Id: I1224ab1cb4c399f5e9cb2001524ef53cca6d83bc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1875277
Auto-Submit: John Wu <jzw@chromium.org>
Reviewed-by: Hiroshi Ichikawa <ichikawa@chromium.org>
Commit-Queue: Hiroshi Ichikawa <ichikawa@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708926}

ios/web_view/internal/autofill/cwv_autofill_suggestion.mm

@@ -46,7 +46,12 @@
 }
 
 - (NSString*)displayDescription {
-  return [_formSuggestion.displayDescription copy];
+  if ([self isPasswordSuggestion]) {
+    // An opaque password string used to hide the true length of the password.
+    return @"••••••••";
+  } else {
+    return [_formSuggestion.displayDescription copy];
+  }
 }
 
 - (UIImage* __nullable)icon {