PgUp PgDown to PageUp PageDown

tower: https://tower.im/projects/d4e0ff64158645f28d99a9ca72d0c27b/todos/a1581f6c86aa4d8591bb7366ce7704b3

Change-Id: I4a379e0b10b95a699719fd45139f6d904d49f3a3
resolve the issue that playlist bounces too high

tower: https://tower.im/projects/d4e0ff64158645f28d99a9ca72d0c27b/todos/498be790d69943fc9402bc0339ae2c57

Change-Id: I92de50805f6b7611051c658cd81db146fd3a5f84