[Autofill] Add a comment about itemTag param

This patch means adding a comment about itemTag param on
addToAutofillSuggestionArray function.

Bug: None
Change-Id: Ib910310e8a084ede503174969a5d8b3d42ba0c0c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2612258Reviewed-by: Dominic Battré <battre@chromium.org>
Commit-Queue: Jaeyong Bae <jdragon.bae@gmail.com>
Cr-Commit-Position: refs/heads/master@{#842213}

chrome/android/java/src/org/chromium/chrome/browser/autofill/AutofillPopupBridge.java

@@ -160,6 +160,7 @@ public class AutofillPopupBridge implements AutofillDelegate, DialogInterface.On
      * @param index Index in the array where to place a new suggestion.
      * @param label First line of the suggestion.
      * @param sublabel Second line of the suggestion.
+     * @param itemTag The offer label of the suggestion.
      * @param iconId The resource ID for the icon associated with the suggestion, or 0 for no icon.
      * @param isIconAtStart {@code true} if {@param iconId} is displayed before {@param label}.
      * @param suggestionId Identifier for the suggestion type.