fenix/app/src/main/res/layout/share_to_apps.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- This Source Code Form is subject to the terms of the Mozilla Public
   - License, v. 2.0. If a copy of the MPL was not distributed with this
   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
<HorizontalScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/apps_layout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <ProgressBar
            android:id="@+id/progressBar"
            android:layout_width="76dp"
            android:layout_height="37dp"
            android:layout_marginTop="@dimen/share_progress_bar_margin"
            android:layout_marginBottom="@dimen/share_progress_bar_margin"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@id/apps_link_header" />

        <LinearLayout
            android:id="@+id/recentAppsContainer"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="@dimen/share_recent_apps_margin"
            android:layout_marginTop="@dimen/share_recent_apps_margin"
            android:layout_marginBottom="@dimen/share_recent_apps_margin"
            android:background="@drawable/recent_apps_background"
            android:orientation="vertical"
            android:paddingTop="@dimen/share_recent_apps_padding"
            android:visibility="gone"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent">

            <TextView
                android:id="@+id/recent_apps_link_header"
                style="@style/ShareHeaderTextStyle"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:paddingStart="@dimen/share_recent_apps_padding"
                android:paddingEnd="@dimen/share_recent_apps_padding"
                android:text="@string/share_link_recent_apps_subheader" />

            <androidx.recyclerview.widget.RecyclerView
                android:id="@+id/recentAppsList"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:clipToPadding="false"
                android:minHeight="@dimen/share_list_min_height"
                android:orientation="horizontal"
                app:layoutManager="androidx.recyclerview.widget.GridLayoutManager"
                app:spanCount="2" />

        </LinearLayout>

        <TextView
            android:id="@+id/apps_link_header"
            style="@style/ShareHeaderTextStyle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="@dimen/share_all_apps_header_margin"
            android:layout_marginTop="@dimen/share_all_apps_header_margin"
            android:text="@string/share_link_all_apps_subheader"
            app:layout_constraintStart_toEndOf="@+id/recentAppsContainer"
            app:layout_constraintTop_toTopOf="parent" />

        <!-- Having the RecyclerView inside a RelativeLayout means
             the RecyclerView will load all items at once and never recycle.
             This is a conscious choice since we use HorizontalScrollView to scroll all
             children horizontally and so prevent scrolling in the RecyclerViews. -->
        <RelativeLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toEndOf="@+id/recentAppsContainer"
            app:layout_constraintTop_toBottomOf="@id/apps_link_header">

            <androidx.recyclerview.widget.RecyclerView
                android:id="@+id/appsList"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginBottom="@dimen/share_all_apps_list_margin"
                android:clipToPadding="false"
                android:minHeight="@dimen/share_list_min_height"
                android:orientation="horizontal"
                android:visibility="gone"
                app:layoutManager="androidx.recyclerview.widget.GridLayoutManager"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent"
                app:spanCount="2" />
        </RelativeLayout>
    </androidx.constraintlayout.widget.ConstraintLayout>
</HorizontalScrollView>