How do you scroll a GridLayout inside Kivy ScrollView?

According to the documentation for ScrollView you have to disable at least one of the ScrollView's child size_hint:

<Controller>:
    layout_content: layout_content
    BoxLayout:
        id: bl
        orientation: 'vertical'
        padding: 10, 10
        row_default_height: '48dp'
        row_force_default: True
        spacing: 10, 10
        ScrollView:
            size: self.size
            GridLayout:
                id: layout_content
                size_hint_y: None
                cols: 1
                row_default_height: '20dp'
                row_force_default: True
                spacing: 0, 0
                padding: 0, 0

                Label:
                    text: "Lorem ipsum dolor sit amet"

And bind the layout's size to adapt itself:

# main.py

class Controller(FloatLayout):
    layout_content=ObjectProperty(None)

    def __init__(self, **kwargs):
        super(Controller, self).__init__(**kwargs)
        self.layout_content.bind(minimum_height=self.layout_content.setter('height'))