Is there an official API for centered title on Toolbar like on popular Android apps, in the new material design?
TL;DR: No, there's currently no official way to center the title on a toolbar.
I don't think there is an official way to do it, at least not yet. But I know that the Flutter framework supports it and it's pretty straight forward: you simply need to pass centerTitle: true
to the appbar constructor, as described in this answer. And there's a good chance that the apps you've mentioned in your question were built with Flutter, since both are from Google.
I think the closest workaround to your expected layout is having the TextView on top of the Toolbar, as shown here:
<android.support.design.widget.AppBarLayout
android:id="@+id/appbar_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/ThemeOverlay.AppCompat.ActionBar">
</android.support.v7.widget.Toolbar>
<TextView
android:layout_centerInParent="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/app_name"/>
</RelativeLayout>
</android.support.design.widget.AppBarLayout>
But it would be really nice if the official Android API could support this the same way flutter does. Maybe you'd like to send a feature request to the Material Components Android Issue Tracker?