Android 8.1 OTG U盤無法顯示在系統文件管理的修改

文件：frameworks\base\services\core\java\com\android\server\StorageManagerService.java
函數：private void onVolumeCreatedLocked(VolumeInfo vol)

如下修改：

    private void onVolumeCreatedLocked(VolumeInfo vol) {
		......

        if (vol.type == VolumeInfo.TYPE_EMULATED) {
        
		......
		
        } else if (vol.type == VolumeInfo.TYPE_PUBLIC) {
			......

            // Adoptable public disks are visible to apps, since they meet
            // public API requirement of being in a stable location.
            /**********************************************************************/
            //if (vol.disk.isAdoptable()) {		//註釋掉這個判斷
                vol.mountFlags |= VolumeInfo.MOUNT_FLAG_VISIBLE;
            //}
            /**********************************************************************/

			......
    }