Hey, thank you for your effort. The FAB looks really good.
To further follow the new design guideline I would suggest that you extend your
method by one line.
public void setFabDrawable(Drawable fabDrawable)
Drawable myDrawable = fabDrawable;
mBitmap = ((BitmapDrawable) myDrawable).getBitmap();
mBitmap = Bitmap.createScaledBitmap(mBitmap, dpToPx(24), dpToPx(24), true);
This makes the fabIcon as big as it should be regardless the source.