title: CollapsingToolbarLayout and imageview inside it do not collapse
body: <p>I want the toolbar and imageview to collapse, when the user scrolls up. Since I'm not using a recyclerview, a suggested workaround was to wrap the imageview in a NestedScrollView. </p>
  
  <p>All of the content below the AppBarLayout, is made up of imageviews, textviews, and many kinds of layouts. By default such content does not scroll, so I wrapped it in a NestedScrollView. This makes the content scroll-able. the problem is, that scrolling up now only makes the bottom NestedScrollView move, and the toolbar does not collapse.</p>
  
  <pre><code>  &lt;?xml version="1.0" encoding="utf-8"?&gt;
      &lt;LinearLayout 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:orientation="vertical"
          tools:context="com.solidcolorlabs.android.solid.activities.ExampleActivity"&gt;
  
          &lt;android.support.design.widget.AppBarLayout
              android:id="@+id/app_bar"
              android:layout_width="match_parent"
              android:layout_height="200dp"&gt;
  
              &lt;android.support.design.widget.CollapsingToolbarLayout
                  android:id="@+id/collapsingToolbarLayout"
                  android:layout_width="match_parent"
                  android:layout_height="match_parent"
                  app:contentScrim="?attr/colorPrimary"
                  app:layout_scrollFlags="scroll|exitUntilCollapsed"&gt;
  
                  &lt;android.support.v4.widget.NestedScrollView
                      android:layout_width="match_parent"
                      android:layout_height="match_parent"
                      app:layout_behavior="@string/appbar_scrolling_view_behavior"
                      app:layout_collapseMode="parallax"
                      app:layout_scrollFlags="scroll"&gt;
  
                          &lt;ImageView
                              android:id="@+id/venue_image"
                              android:layout_width="match_parent"
                              android:layout_height="200dp" /&gt;
  
                  &lt;/android.support.v4.widget.NestedScrollView&gt;
  
                  &lt;android.support.v7.widget.Toolbar
                      android:id="@+id/toolbar"
                      android:layout_width="match_parent"
                      android:layout_height="?android:attr/actionBarSize"
                      android:minHeight="?attr/actionBarSize"
                      android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
                      app:layout_collapseMode="pin"
                      app:navigationContentDescription="@string/abc_action_bar_up_description"
                      app:popupTheme="@style/ThemeOverlay.AppCompat.Light"&gt;
  
                  &lt;/android.support.v7.widget.Toolbar&gt;
  
              &lt;/android.support.design.widget.CollapsingToolbarLayout&gt;
  
          &lt;/android.support.design.widget.AppBarLayout&gt;
  
          &lt;android.support.v4.widget.NestedScrollView
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              app:layout_behavior="@string/appbar_scrolling_view_behavior"
              app:layout_collapseMode="parallax"
              app:layout_scrollFlags="scroll"&gt;
  
              &lt;LinearLayout
                  android:layout_width="match_parent"
                  android:layout_height="match_parent"
                  android:orientation="vertical"&gt;
  
                        ...
  
              &lt;/LinearLayout&gt;
  
          &lt;/android.support.v4.widget.NestedScrollView&gt;
  
      &lt;/LinearLayout&gt;
  </code></pre>