Merge "Fix NPE in ChooseLockPattern"

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.LinearLayout;

import android.widget.ScrollView;

import android.widget.TextView;

import com.google.android.setupcompat.template.FooterButton;

import com.google.android.setupdesign.GlifLayout;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.List;

        public void handleLeftButton() {

            if (mUiStage.leftMode == LeftButtonMode.Retry) {

                if (mChosenPattern != null) {

                    mChosenPattern.zeroize();

                    mChosenPattern = null;

                }

                mLockPatternView.clearPattern();

                updateStage(Stage.Introduction);

            } else {