title: Issues with positioning Toolbar and FAB in ConstraintLayout
body: <p>I have been using this code inside Co-ordinatorLayout, with no issues. I tried tweaking the code to work inside ConstraintLayout. While displaying Snackbar, the Snackbar is overlapping FAB. Also, I am unable to auto hide Toolbar. Can someone guide on how to auto-hide Toolbar and FAB inside ConstraintLayout.</p>
  
  <pre><code>&lt;android.support.constraint.ConstraintLayout 
      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:id="@+id/acbl_layout_parent"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context="com.sample.android.ActivitySample"&gt;
  
      &lt;!--Toolbar--&gt;
      &lt;android.support.design.widget.AppBarLayout
          android:id="@+id/acbl_layout_toolbar"
          android:layout_width="0dp"
          android:layout_height="wrap_content"
          app:layout_constraintEnd_toEndOf="parent"
          app:layout_constraintStart_toStartOf="parent"
          app:layout_constraintTop_toTopOf="parent"&gt;
  
          &lt;include layout="@layout/toolbar" /&gt;
  
      &lt;/android.support.design.widget.AppBarLayout&gt;
  
      &lt;!--Layout--&gt;
      &lt;android.support.v7.widget.RecyclerView
          android:id="@+id/recyclerView"
          android:layout_width="match_parent"
          android:layout_height="wrap_content" /&gt;
  
      &lt;!--FAB--&gt;
      &lt;android.support.design.widget.FloatingActionButton
          android:id="@+id/fab"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_margin="@dimen/dp_16"
          app:fabSize="normal"
          app:layout_anchor="parent"
          app:layout_anchorGravity="bottom|end"
          app:layout_constraintBottom_toBottomOf="parent"
          app:layout_constraintEnd_toEndOf="parent"
          app:srcCompat="@drawable/icon_add" /&gt;
  
  &lt;/android.support.constraint.ConstraintLayout&gt;
  </code></pre>