Merge "Update libdvrtracking doc"

//     populate the buffer into. The queue must be empty and the camera stack

//     will request buffer allocation with proper buffer dimension, format, and

//     usage. Note that the write queue must be created with user_metadata_size

//     set to sizeof(DvrTrackingBufferMetadata).

//     set to sizeof(DvrTrackingBufferMetadata). On success, the write_queue

//     handle will become invalid and the ownership of the queue handle will be

//     transferred into the camera; otherwise, the write_queue handle will keep

//     untouched and the caller still has the ownership.

// @return Zero on success, or negative error code.

int dvrTrackingCameraStart(DvrTrackingCamera* camera,

                           DvrWriteBufferQueue* write_queue);