Collapsing Toolbar Layout using Google Design Library

Acitivity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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:fitsSystemWindows="true"
    tools:context=".ScrollingActivity">

    <android.support.design.widget.AppBarLayout android:id="@+id/app_bar"
        android:fitsSystemWindows="true" android:layout_height="@dimen/app_bar_height"
        android:layout_width="match_parent" android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.design.widget.CollapsingToolbarLayout android:id="@+id/toolbar_layout"
            android:fitsSystemWindows="true" android:layout_width="match_parent"
            android:layout_height="match_parent" app:layout_scrollFlags="scroll|exitUntilCollapsed"
            app:contentScrim="?attr/colorPrimary">
            <ImageView
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:scaleType="fitXY"
                android:src="@drawable/logo"/>

            <android.support.v7.widget.Toolbar android:id="@+id/toolbar"
                android:layout_height="?attr/actionBarSize" android:layout_width="match_parent"
                app:layout_collapseMode="pin" app:popupTheme="@style/AppTheme.PopupOverlay" />

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

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

    <android.support.design.widget.FloatingActionButton android:id="@+id/fab"
        android:layout_width="wrap_content" android:layout_height="wrap_content"
        android:layout_margin="@dimen/fab_margin" app:layout_anchor="@id/app_bar"
        app:layout_anchorGravity="bottom|end" android:src="@android:drawable/ic_dialog_email" />

</android.support.design.widget.CoordinatorLayout>