why the CoordinatorLayout show white space in the bottom?

HI I have main activity XML as below

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">

<android.support.design.widget.CoordinatorLayout 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="#FFFFFF"
    android:fitsSystemWindows="true"
    tools:context=".MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="@dimen/abc_action_bar_default_height_material"
            android:background="@color/fcolor"
            app:popupTheme="@style/AppTheme.PopupOverlay">

            <TextView
                android:id="@+id/toolbar_title"
                style="@style/TextAppearance.AppCompat.Widget.ActionBar.Title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:text="text"
                android:textColor="@color/scolor" />
        </android.support.v7.widget.Toolbar>

        <android.support.design.widget.TabLayout
            android:id="@+id/tab_layout"
            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:layout_below="@+id/toolbar"
            android:background="?attr/colorPrimary"
            android:elevation="2dp"
            android:minHeight="?attr/actionBarSize"
            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
            app:tabGravity="fill"
            app:tabMode="fixed" />
    </android.support.design.widget.AppBarLayout>

    <include layout="@layout/content_main" />
</android.support.design.widget.CoordinatorLayout>


<android.support.design.widget.NavigationView
    android:id="@+id/nvView"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:background="@android:color/white"
    app:headerLayout="@layout/navigation_header"
    app:menu="@menu/drawer_view" />

As you can see I add my main content inside the CoordinatorLayout using Include Tag

  <include layout="@layout/content_main" />

in content main XML, I have

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/actvity_main" tools:context=".Main">
<android.support.v4.view.ViewPager
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="fill_parent"
    android:layout_below="@id/tab_layout"/>

 </RelativeLayout>

then I used different XML layout have Mapview within RelativeLayout to show in the page viewer

my problem that always there's empty space in the bottom of the screen left from the CoordinatorLayout as the below image

As you can see there's white space in the bottom, the reason why I know it's from CoordinatorLayout because when I change the CoordinatorLayout background it changes the space color

it seems like my include tag not scale in hight for all the screen, even when I set

    <include
        layout="@layout/content_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

still the same, what I need is to make my Mapview scale and fill the bottom of the screen

In main.xml, remove android:paddingBottom="3dp".