apps/OboeTester/app/src/main/res/layout/activity_error_callback.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".TestErrorCallbackActivity">

    <GridLayout
        android:id="@+id/buttonGrid"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:columnCount="1">

    <Button
        android:id="@+id/buttonTestDeleteCrash"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_columnWeight="1"
        android:layout_gravity="fill"
        android:backgroundTint="@color/button_tint"
        android:onClick="onTestDeleteCrash"
        android:text="Delete Callback" />

    <TextView
        android:id="@+id/text_callback_status"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fontFamily="monospace"
        android:gravity="bottom"
        android:text="@string/init_status"
        />

</GridLayout>
</android.support.constraint.ConstraintLayout>