main_res_layout_activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    android:background="@android:color/white"
    android:backgroundTint="@android:color/white"
    tools:context="com.example.harsh.freechat.MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <include
            android:id="@+id/main_page_toolbar"
            layout="@layout/app_bar_layout" />

        <android.support.design.widget.TabLayout
            android:id="@+id/main_tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:backgroundTint="@android:color/white"
            app:tabSelectedTextColor="@android:color/white"
            app:tabTextColor="@color/colorAccent">

        </android.support.design.widget.TabLayout>
    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/main_tabPager"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="100dp"
        app:layout_constraintTop_toTopOf="parent"></android.support.v4.view.ViewPager>


</RelativeLayout>