core/res/res/layout/notification_template_icon_group.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  ~ Copyright (C) 2014 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
  -->

<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:internal="http://schemas.android.com/apk/prv/res/android"
    android:layout_width="@dimen/notification_large_icon_width"
    android:layout_height="@dimen/notification_large_icon_height"
    android:id="@+id/icon_group"
    >
    <ImageView android:id="@+id/icon"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="12dp"
        android:layout_marginBottom="12dp"
        android:layout_marginStart="12dp"
        android:layout_marginEnd="12dp"
        android:scaleType="centerInside"
        />
    <ImageView android:id="@+id/right_icon"
        android:layout_width="16dp"
        android:layout_height="16dp"
        android:padding="3dp"
        android:layout_gravity="end|bottom"
        android:scaleType="centerInside"
        android:visibility="gone"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        />
</FrameLayout>