Add view inside toolbar.

toolbar_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="?attr/colorPrimary"
    android:minHeight="?attr/actionBarSize"
    app:contentInsetLeft="0dp"
    app:contentInsetStart="0dp"
    app:titleTextColor="@android:color/white"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
    app:layout_scrollFlags="scroll|enterAlways">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal">

            <ImageView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:src="@mipmap/ic_launcher"/>

            <TextView
                android:id="@+id/toolbar_title"
                android:layout_marginLeft="16dp"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="toolbar title"
                android:textColor="@android:color/white"
                android:layout_marginTop="16dp"
                style="@style/TextAppearance.AppCompat.Widget.ActionBar.Title"/>

            </LinearLayout>
            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="subtitle caranchoa"
                android:layout_margin="50dp"
                android:textAlignment="center"
                android:textAppearance="@style/Base.TextAppearance.AppCompat.Display1"
                android:textColor="@android:color/white"/>
        </LinearLayout>
    </android.support.v7.widget.Toolbar>