title: setTooltipText() and android:tooltipText are not working in Nougat
body: <p>I have an ImageButton, when I did some test for my app, I found that I could not show the <code>tooltipText</code> in my Xiaomi Note 4 with Android N device. But it shows up perfectly fine in my Samsung S8 with Android O, any idea why this can happen and how to mitigate this? The minimum reproducible code is really simple, just create a basic android project in android studio and replace the default HelloWorld Textview to </p>
  
  <pre><code>&lt;ImageButton
          android:layout_width="36dp"
          android:layout_height="36dp"
          android:tooltipText="Show tooltip"
          android:src="@mipmap/ic_launcher"
          app:layout_constraintBottom_toBottomOf="parent"
          app:layout_constraintLeft_toLeftOf="parent"
          app:layout_constraintRight_toRightOf="parent"
          app:layout_constraintTop_toTopOf="parent" /&gt;
  </code></pre>
  
  <p>I think there must be some way I can make it work because the auto generated toolbar obviously has tooltip. So there must be something I'm missing to make it work in Xiaomi device.</p>