[Autofill Assistant] Bugfix preference.

Before this patch we would add a settings entry on every resume of the activity.
This patch only adds the entry once on creation and not on every onResume.

Bug: 806868
Change-Id: I6d41d99f6f2d05ad98e306da2c6bdebed7c37722
Reviewed-on: https://chromium-review.googlesource.com/c/1318970Reviewed-by: Stephane Zermatten <szermatt@chromium.org>
Commit-Queue: Mathias Carlen <mcarlen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605661}

chrome/android/java/src/org/chromium/chrome/browser/preferences/autofill_assistant/AutofillAssistantPreferences.java

@@ -23,11 +23,6 @@ public class AutofillAssistantPreferences extends PreferenceFragment {
         super.onCreate(savedInstanceState);
         getActivity().setTitle(R.string.prefs_autofill_assistant_title);
         setPreferenceScreen(getPreferenceManager().createPreferenceScreen(getActivity()));
-    }
-
-    @Override
-    public void onResume() {
-        super.onResume();
         createAutofillAssistantSwitch();
     }