title: Android support Toolbar + ActionBarDrawerToggle not changing to arrow
body: <p>I'm struggling with the toolbar and drawer. I'm trying to make the burger switch to arrow when I'm adding a new fragment to the backstack but there is no way to do it.</p>
  
  <p>Maybe I'm missing something but I could not find a way. Anyone had the same problem?</p>
  
  <p>This is the declaration:</p>
  
  <pre><code>mDrawerToggle = new ActionBarDrawerToggle(
              getActivityCompat(),                    /* host Activity */
              mDrawerLayout,                    /* DrawerLayout object */
              ((BaseActivity) getActivityCompat()).getToolbar(),
              R.string.navigation_drawer_open,  /* "open drawer" description for accessibility */
              R.string.navigation_drawer_close  /* "close drawer" description for accessibility */
      )
  </code></pre>
  
  <p>This is the function I call when a fragment is added to the back stack</p>
  
  <pre><code>public void setToggleState(boolean isEnabled) {
      if (mDrawerLayout == null)
          return;
  
      if (isEnabled) {
          mDrawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED);
          mDrawerToggle.onDrawerStateChanged(DrawerLayout.LOCK_MODE_UNLOCKED);
      } else {
          mDrawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED);
          mDrawerToggle.onDrawerStateChanged(DrawerLayout.LOCK_MODE_LOCKED_CLOSED);
      }
      mDrawerToggle.syncState();
  }
  </code></pre>