I am using the following code to pick images.
Intent photoPickerIntent = new Intent(Intent.ACTION_PICK);
photoPickerIntent.setType("image/*");
photoPickerIntent.setData(android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(Intent.createChooser(photoPickerIntent, getActivity().getResources().getString(R.string.select_picture)), 1);
Its working fine but it only let me to choose images from default Photos application. I want to pick images from "Gallery" application even in today's latest devices. I don't know how WhatsApp is doing this even for Lollipop.