foo.java

    void addToUI(int width, int height, boolean isTopBanner) {
        float density = activity.getResources().getDisplayMetrics().density;
        int finalWidth = (int)(width * density);
        int finalHeight = (int)(height * density);

        bannerFrame = new FrameLayout(activity);
        bannerFrame.addView(banner, new FrameLayout.LayoutParams(
                finalWidth, finalHeight,
                (isTopBanner ? Gravity.TOP : Gravity.BOTTOM) | Gravity.CENTER_HORIZONTAL
        ));

        ViewGroup root = (ViewGroup) activity.getWindow().getDecorView();
        root.addView(bannerFrame, new ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT
        ));

        Log.d(TAG, "Banner added to UI.");
        setVisibilityUI(false);
    }