title: Zoom in on AppBarLayout on overscroll downwards
body: <p>I've been struggling for quite some time to achieve a zoom effect on AppBarLayout when pulling down anywhere on the page (overscroll).  </p>
  
  <p>Example of desired effect:
  <a href="https://android-arsenal.com/details/1/4443" rel="nofollow noreferrer">https://android-arsenal.com/details/1/4443</a></p>
  
  <p>My layout has the following layout (removed irrelevant views):</p>
  
  <pre><code>--CoordinatorLayout
      -- AppBarLayout
          -- CollapsingToolbarLayout
               --FrameLayout
                   --ImageView
      -- NestedScrollView
          -- ...
  </code></pre>
  
  <p>I've managed to get somewhat close to the desired behavior when overscrolling the NestedScrollView (with help from <a href="https://medium.com/@nullthemall/overscroll-appbarlayout-behavior-e58f1ee2807#.7fjf1nz2b" rel="nofollow noreferrer">this</a>) but I've had no luck triggering the behavior when overscrolling on the AppBarLayout.</p>
  
  <p>Any suggestions?</p>