title: Issue with Toolbar in CollapsingToolbarlayout
body: <p>I started using a collapsing toolbar in my app. After implementing it the way they did on the Android developers blog, it doesn't seem to be working correctly. I see the overflow and up navigation button, however they don't follow the toolbar when I scroll downwards. This <a href="http://material-design.storage.googleapis.com/publish/material_v_4/material_ext_publish/0B6Okdz75tqQscXNQY3dNdVlYeTQ/patterns-scrolling-techniques_flex_space_image_xhdpi_003.webm" rel="nofollow">video</a> is what should be happening, everything works fine except for the fact that the overflow/up navigation icons don't display on the collapsed toolbar.</p>
  
  <p>Projects Detail Activity
  package com.austinerck.projectpanda.activity;</p>
  
  <pre><code>import android.support.design.widget.CollapsingToolbarLayout;
  import android.support.v7.app.AppCompatActivity;
  import android.os.Bundle;
  import android.support.v7.widget.Toolbar;
  import android.view.Menu;
  import android.view.MenuItem;
  
  import com.austinerck.projectpanda.R;
  
  public class ProjectDetailsActivity extends AppCompatActivity {
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_project_details);
          final Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
          setSupportActionBar(toolbar);
          getSupportActionBar().setDisplayHomeAsUpEnabled(true);
  
          CollapsingToolbarLayout collapsingToolbar = (CollapsingToolbarLayout) findViewById(R.id.toolbar_collapse);
          collapsingToolbar.setTitle("Project Name");
      }
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
          // Inflate the menu; this adds items to the action bar if it is present.
          getMenuInflater().inflate(R.menu.menu_project_details, menu);
          return true;
      }
  
      @Override
      public boolean onOptionsItemSelected(MenuItem item) {
          // Handle action bar item clicks here. The action bar will
          // automatically handle clicks on the Home/Up button, so long
          // as you specify a parent activity in AndroidManifest.xml.
          int id = item.getItemId();
  
          //noinspection SimplifiableIfStatement
          if (id == R.id.action_settings) {
              return true;
          }
  
          return super.onOptionsItemSelected(item);
      }
  }
  </code></pre>
  
  <p>activity_project_details.xml
  </p>
  
  <pre><code>    &lt;android.support.design.widget.AppBarLayout
          android:layout_height="192dp"
          android:layout_width="match_parent"&gt;
  
          &lt;android.support.design.widget.CollapsingToolbarLayout
              android:id="@+id/toolbar_collapse"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              app:contentScrim="?attr/colorPrimary"
              app:layout_scrollFlags="scroll|exitUntilCollapsed"&gt;
  
              &lt;android.support.v7.widget.Toolbar
                  android:id="@+id/toolbar"
                  android:layout_height="?attr/actionBarSize"
                  android:layout_width="match_parent"
                  app:layout_collapseMode="parallax"/&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"
          android:layout_gravity="fill_vertical"
          app:layout_behavior="@string/appbar_scrolling_view_behavior"&gt;
  
          &lt;LinearLayout
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical"
              android:paddingTop="24dp"&gt;
  
              &lt;android.support.v7.widget.CardView
                  android:layout_marginLeft="10dp"
                  android:layout_marginRight="10dp"
                  android:layout_marginTop="10dp"
                  android:layout_width="match_parent"
                  android:layout_height="wrap_content"&gt;
  
                  &lt;LinearLayout
                      android:orientation="vertical"
                      android:layout_width="match_parent"
                      android:layout_height="wrap_content"&gt;
  
                      &lt;TextView
                          android:layout_width="match_parent"
                          android:layout_height="wrap_content"
                          android:textColor="@color/error_color"
                          android:textSize="20sp"
                          android:text="This text is part of first Cardview\n\n"/&gt;
  
                  &lt;/LinearLayout&gt;
  
              &lt;/android.support.v7.widget.CardView&gt;
  
              &lt;android.support.v7.widget.CardView
                  android:layout_marginLeft="10dp"
                  android:layout_marginRight="10dp"
                  android:layout_marginTop="10dp"
                  android:layout_width="match_parent"
                  android:layout_height="wrap_content"&gt;
  
                  &lt;LinearLayout
                      android:orientation="vertical"
                      android:layout_width="match_parent"
                      android:layout_height="wrap_content"&gt;
  
                      &lt;TextView
                          android:layout_width="match_parent"
                          android:layout_height="wrap_content"
                          android:textSize="20sp"
                          android:textColor="@color/abc_search_url_text"
                          android:text="This text is part of second Cardview\n\n"/&gt;
  
                  &lt;/LinearLayout&gt;
  
              &lt;/android.support.v7.widget.CardView&gt;
  
          &lt;/LinearLayout&gt;
  
          &lt;/android.support.v4.widget.NestedScrollView&gt;
  
      &lt;/android.support.design.widget.CoordinatorLayout&gt;
  </code></pre>