android/support/design/widget/BottomSheetDialog.java of Android Design Support Library 23.4.0

BottomSheetDialog.java

private View wrapInBottomSheet(int layoutResId, View view, ViewGroup.LayoutParams params) {
    final CoordinatorLayout coordinator = (CoordinatorLayout) View.inflate(getContext(),
            R.layout.design_bottom_sheet_dialog, null);
    if (layoutResId != 0 && view == null) {
        view = getLayoutInflater().inflate(layoutResId, coordinator, false);
    }
    FrameLayout bottomSheet = (FrameLayout) coordinator.findViewById(R.id.design_bottom_sheet);
    BottomSheetBehavior.from(bottomSheet).setBottomSheetCallback(mBottomSheetCallback);
    if (params == null) {
        bottomSheet.addView(view);
    } else {
        bottomSheet.addView(view, params);
    }
    // We treat the CoordinatorLayout as outside the dialog though it is technically inside
    if (shouldWindowCloseOnTouchOutside()) {
        coordinator.findViewById(R.id.touch_outside).setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        if (isShowing()) {
                            cancel();
                        }
                    }
                });
    }
    return coordinator;
}

...

private BottomSheetBehavior.BottomSheetCallback mBottomSheetCallback
        = new BottomSheetBehavior.BottomSheetCallback() {
    @Override
    public void onStateChanged(@NonNull View bottomSheet,
            @BottomSheetBehavior.State int newState) {
        if (newState == BottomSheetBehavior.STATE_HIDDEN) {
            dismiss();
        }
    }

    @Override
    public void onSlide(@NonNull View bottomSheet, float slideOffset) {
    }
};