You can use ArcLayout library.
Add dependency to build.gradle(app level)
compile 'com.github.florent37:arclayout:1.0.3'
Add ArcLayout to your xml it can make curve inside or outside, inside in your case, so use this app:arc_cropDirection="cropInside"
property.
<com.github.florent37.arclayout.ArcLayout
android:layout_width="match_parent"
android:layout_height="200dp"
app:arc_cropDirection="cropInside"
app:arc_height="90dp"
app:arc_padding="30dp"
android:elevation="5dp"
>
<!--Your layout will be here to make toolbar -->