AndroidManifestForFcm.xml

There's a version of AndroidManifest.xml that's generated by Xamarin Studio at https://gist.github.com/banshee/eb7cdd94652e21ca0aeaeb3978c9da06.
(That gist does not contain the manual changes for com.google.firebase.iid.FirebaseInstanceIdReceiver and com.google.firebase.iid.FirebaseInstanceIdInternalReceiver.)

<?xml version="1.0" encoding="utf-8"?>
<manifest
    xmlns:android="http://schemas.android.com/apk/res/android">

    <!--Xamarin.Firebase.Iid/library_project_imports/AndroidManifest.xml-->
    <uses-permission
        android:name="android.permission.WAKE_LOCK" />

    <!--Xamarin.Firebase.Iid/library_project_imports/AndroidManifest.xml-->
    <uses-permission
        android:name="com.google.android.c2dm.permission.RECEIVE" />

    <!--Xamarin.Firebase.Iid/library_project_imports/AndroidManifest.xml declares a new permission for your app using -->
    <!-- <permission android:name="${applicationId}.permission.C2D_MESSAGE" android:protectionLevel="signature"/> -->
    <!--Xamarin build doesn't include this -->
    <permission
        android:name="example.com.fcmproject.permission.C2D_MESSAGE"
        android:protectionLevel="0x2" />

    <!--and then it uses that permission-->
    <!--Xamarin build doesn't include this -->
    <uses-permission
        android:name="example.com.fcmproject.permission.C2D_MESSAGE" />

    <application>
        <!--normal Firebase service definition, added by hand by the user-->
        <service
            android:name="example.com.fcmproject.MyFirebaseMessagingService">

            <intent-filter>

                <action
                    android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>

        <!--Added by Android tooling-->
        <!--In Xamarin, added in Xamarin.Firebase.Messaging/library_project_imports/AndroidManifest.xml-->
        <service
            android:name="com.google.firebase.messaging.FirebaseMessagingService"
            android:exported="true">

            <intent-filter
                android:priority="-500">

                <action
                    android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>

        <!--Xamarin.Firebase.Iid/library_project_imports/AndroidManifest.xml-->
        <!--Xamarin build doesn't include this-->
        <!-- https://developer.xamarin.com/guides/android/application_fundamentals/notifications/remote-notifications-with-fcm/#backnotif
        does tell you to add it by hand-->
        <receiver
            android:name="com.google.firebase.iid.FirebaseInstanceIdReceiver"
            android:permission="com.google.android.c2dm.permission.SEND"
            android:exported="true">

            <intent-filter>

                <action
                    android:name="com.google.android.c2dm.intent.RECEIVE" />

                <action
                    android:name="com.google.android.c2dm.intent.REGISTRATION" />

                <category
                    android:name="example.com.fcmproject" />
            </intent-filter>
        </receiver>

        <!--Xamarin.Firebase.Iid/library_project_imports/AndroidManifest.xml-->
        <!--Xamarin build doesn't include this-->
        <receiver
            android:name="com.google.firebase.iid.FirebaseInstanceIdInternalReceiver"
            android:exported="false" />

        <!--Xamarin.Firebase.Iid/library_project_imports/AndroidManifest.xml-->
        <!--Xamarin build doesn't include this-->
        <service
            android:name="com.google.firebase.iid.FirebaseInstanceIdService"
            android:exported="true">

            <intent-filter
                android:priority="-500">

                <action
                    android:name="com.google.firebase.INSTANCE_ID_EVENT" />
            </intent-filter>
        </service>

        <!--Xamarin.Firebase.Common/library_project_imports/AndroidManifest.xml-->
        <provider
            android:name="com.google.firebase.provider.FirebaseInitProvider"
            android:exported="false"
            android:authorities="example.com.fcmproject.firebaseinitprovider"
            android:initOrder="100" />

        <meta-data
            android:name="com.google.android.gms.version"
            android:value="@ref/0x7f0c0003" />

    </application>
</manifest>

This is just stripped down XML that's used in an Android app that's receiving FCM messages

Added info about the xml generated by Xamarin Studio