title: Toolbar Navigation Hamburger Icon missing
body: <p>I'm looking for a way to display the hamburger icon whitout using the Drawer/DrawerToggle and use the default icon included in Android
  <img src="https://i.stack.imgur.com/xSYDb.png" alt="enter image description here"></p>
  
  <p>By setting <code>getSupportActionBar().setDisplayHomeAsUpEnabled(true);</code> it display the back arrow but not the hambuerger. Other post on Stackoverflow (like <a href="https://stackoverflow.com/questions/26525229/toolbar-navigation-icon-never-set">this</a> or <a href="https://stackoverflow.com/questions/26754940/appcompatv7-v21-navigation-drawer-not-showing-hamburger-icon">this</a>) use the DrawerLayout or a custom drawable. I cannot find the vector or png for the hamburger icon on the Android source. </p>
  
  <p><strong>Do you know how can I find the original hamburger icon in android/support library?</strong> (or how to displayed it)</p>
  
  <p><em>Note:  Vector and png can be found on google.com/design website :</em> <a href="http://www.google.com/design/spec/resources/sticker-sheets-icons.html#" rel="noreferrer">http://www.google.com/design/spec/resources/sticker-sheets-icons.html#</a> </p>
  
  <p>In my activity</p>
  
  <pre><code>mToolbar = (Toolbar) findViewById(R.id.toolbar);
  setSupportActionBar(mToolbar);
  getSupportActionBar().setDisplayHomeAsUpEnabled(true);
  getSupportActionBar().setHomeButtonEnabled(true);
  
  mToolbar.setNavigationOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
          Log.d(LOG_TAG, "navigation clicked");
      }
  });
  </code></pre>
  
  <p>Layout file</p>
  
  <pre><code>&lt;android.support.v7.widget.Toolbar
      android:id="@+id/toolbar"
      android:layout_height="wrap_content"
      android:layout_width="match_parent"
      android:minHeight="?attr/actionBarSize"
      android:background="?attr/colorPrimary"
      app:theme="@style/ThemeOverlay.AppCompat.ActionBar"/&gt;
  </code></pre>
  
  <p>Styles.xml </p>
  
  <pre><code>&lt;!-- Base application theme. --&gt;
  &lt;style name="Theme.AppTheme" parent="Theme.AppCompat.Light.NoActionBar"&gt;
  
  
      &lt;item name="colorPrimary"&gt;@color/primaryDef&lt;/item&gt;
      &lt;item name="colorPrimaryDark"&gt;@color/primaryDarkDef&lt;/item&gt;
      &lt;item name="colorAccent"&gt;@color/primaryDef&lt;/item&gt;
  
      &lt;!-- Remove the actionbar shadow--&gt;
      &lt;item name="android:windowContentOverlay"&gt;@null&lt;/item&gt;
  &lt;/style&gt;
  </code></pre>