packages/SystemUI/res/layout/fingerprint_dialog.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  ~ Copyright (C) 2018 The Android Open Source Project
  ~
  ~ Licensed under the Apache License, Version 2.0 (the "License");
  ~ you may not use this file except in compliance with the License.
  ~ You may obtain a copy of the License at
  ~
  ~      http://www.apache.org/licenses/LICENSE-2.0
  ~
  ~ Unless required by applicable law or agreed to in writing, software
  ~ distributed under the License is distributed on an "AS IS" BASIS,
  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  ~ See the License for the specific language governing permissions and
  ~ limitations under the License
  -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="bottom"
    android:background="@color/fingerprint_dialog_dim_color"
    android:orientation="vertical">

    <!-- This is not a Space since Spaces cannot be clicked -->
    <View
        android:id="@+id/space"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <!-- This is not a Space since Spaces cannot be clicked. The width of this changes depending
         on horizontal/portrait orientation -->
        <View
            android:id="@+id/left_space"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="match_parent"/>

        <LinearLayout
            android:id="@+id/dialog"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:elevation="2dp"
            android:background="@drawable/fingerprint_dialog_bg">

            <TextView
                android:id="@+id/title"
                android:fontFamily="@*android:string/config_headlineFontFamilyMedium"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginEnd="24dp"
                android:layout_marginStart="24dp"
                android:layout_marginTop="24dp"
                android:gravity="@integer/fingerprint_dialog_text_gravity"
                android:textSize="20sp"
                android:maxLines="1"
                android:singleLine="true"
                android:ellipsize="marquee"
                android:marqueeRepeatLimit="marquee_forever"
                android:textColor="@color/fingerprint_dialog_text_dark_color"/>

            <TextView
                android:id="@+id/subtitle"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginTop="8dp"
                android:layout_marginStart="24dp"
                android:layout_marginEnd="24dp"
                android:gravity="@integer/fingerprint_dialog_text_gravity"
                android:textSize="16sp"
                android:maxLines="1"
                android:singleLine="true"
                android:ellipsize="marquee"
                android:marqueeRepeatLimit="marquee_forever"
                android:textColor="@color/fingerprint_dialog_text_dark_color"/>

            <TextView
                android:id="@+id/description"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginEnd="24dp"
                android:layout_marginStart="24dp"
                android:gravity="@integer/fingerprint_dialog_text_gravity"
                android:paddingTop="8dp"
                android:textSize="16sp"
                android:maxLines="4"
                android:textColor="@color/fingerprint_dialog_text_dark_color"/>

            <ImageView
                android:id="@+id/fingerprint_icon"
                android:layout_width="@dimen/fingerprint_dialog_fp_icon_size"
                android:layout_height="@dimen/fingerprint_dialog_fp_icon_size"
                android:layout_gravity="center_horizontal"
                android:layout_marginTop="48dp"
                android:scaleType="fitXY"
                android:contentDescription="@string/accessibility_fingerprint_dialog_fingerprint_icon" />

            <TextView
                android:id="@+id/error"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginEnd="24dp"
                android:layout_marginStart="24dp"
                android:paddingTop="16dp"
                android:paddingBottom="24dp"
                android:textSize="12sp"
                android:gravity="center_horizontal"
                android:accessibilityLiveRegion="polite"
                android:text="@string/fingerprint_dialog_touch_sensor"
                android:contentDescription="@string/accessibility_fingerprint_dialog_help_area"
                android:textColor="@color/fingerprint_dialog_text_light_color"/>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="72dip"
                android:paddingTop="24dp"
                android:layout_gravity="center_vertical"
                style="?android:attr/buttonBarStyle"
                android:orientation="horizontal"
                android:measureWithLargestChild="true">
                <Space android:id="@+id/leftSpacer"
                    android:layout_width="24dp"
                    android:layout_height="match_parent"
                    android:visibility="visible" />
                <!-- Negative Button -->
                <Button android:id="@+id/button2"
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    style="@*android:style/Widget.DeviceDefault.Button.Borderless.Colored"
                    android:layout_marginStart="-12dp"
                    android:gravity="start|center_vertical"
                    android:maxLines="2" />
                <!-- Positive Button -->
                <Button android:id="@+id/button1"
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    style="@*android:style/Widget.DeviceDefault.Button.Borderless.Colored"
                    android:layout_marginEnd="12dp"
                    android:maxLines="2" />
                <Space android:id="@+id/rightSpacer"
                    android:layout_width="24dip"
                    android:layout_height="match_parent"
                    android:visibility="gone" />
            </LinearLayout>
        </LinearLayout>

        <!-- This is not a Space since Spaces cannot be clicked. The width of this changes depending
         on horizontal/portrait orientation -->
        <View
            android:id="@+id/right_space"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="match_parent" />

    </LinearLayout>

</LinearLayout>