Document new preview callback methods more clearly.

    }

    /**

     * Adds a pre-allocated buffer to the callback buffer queue.

     * Adds a pre-allocated buffer to the callback buffer queue. Applications

     * can add one or more buffers to the queue. When a preview frame arrives

     * and there is still available buffer, buffer will be filled and it is

     * removed from the queue. Then preview callback is invoked with the buffer.

     * If a frame arrives and there is no buffer left, the frame is discarded.

     * Applications should add the buffers back when they finish the processing.

     *

     * Preview width and height can be determined from getPreviewSize, and bitsPerPixel can be

     * found from {@link android.hardware.Camera.Parameters#getPreviewFormat()}

     * and {@link android.graphics.ImageFormat#getBitsPerPixel(int)}.