It can be done in 4 steps :
- Clone your VMDK to VDI format with VBoxManage Tool.
- Resize the disk to create free space with VBoxManage Tool.
- Modify the filesystem to allocate free space for your drive with GParted.
- Add created disk space to Linux FileSystem.
The detailed steps are below (tested with "Virtual Machine CentOS 6.4" and "VirtualBox 4.2.18");
- Observe disk format of the virtualbox file, if it is not *.vdi, convert disk format from *.wmdk to *.vdi. Open windows terminal: 
 -  $ VBoxManage clonehd --format VDI "path_of_wmdk_file" "path_of_vdi_file"
 
- Resize disk size of vdi file. Open windows terminal. For example to do disk size ~500 GB => 512000; 
 -  $ VBoxManage modifymedium "path_of_vdi_file" --resize 512000
 
- Choose *.vdi file instead of *.wmdk file as disk 
 -  Virtual Machine -> Settings -> Storage -> Controller : SATA (Right Click on *.wmdk file) -> Remove Attachment -> Add HardDisk and choose newly created *.vdi file
 
- Download "gparted-live-x.xx.x-x-ixxx.iso" file from http://gparted.sourceforge.net/download.php. Mount this iso file  as CD.
 -  Virtual Machine -> Settings -> Storage -> Controller IDE (Right Click) -> Add CD/DVD -> Select gparted-live-x.xx.x-x-ixxx.iso file
 
- Run virtual machine, Virtual Machine will boot from this CD. Choose default values with pressing "Enter", "Enter" ... until Gpart ISO GUI starts. Select tool gpart program and start. 
- Extend disk size as below; - 
- Right click on partitions and if "possible" click on "Disable Active Partion".
- Extend Partition as much as possible from GUI (for this case 500GB).
- Right click the partition which is disabled and select "Enable Active Partion".
- Apply and wait until the operations finished.
- Shut down virtual machine.
- Unmount gparted-live-x.xx.x-x-ixxx.iso.
  Virtual Machine -> Settings -> Storage-> Controller IDE (Right Click on gparted-live-x.xx.x-x-ixxx.iso) -> Remove Attachement
- Start the virtual machine.
 
 
 
- Open linux terminal and login as root. Run commands below; 
 lvm vgdisplay
       => Free  PE / Size       122880 / 480.00 GiB
 lvm lvdisplay /dev/VolGroup/lv_root
       => Current LE             3978
- Calculate the sum of the values above. In this case : 122880 + 3978 = 126858 <- will be used in the next command 
 lvm lvresize -l 126858 /dev/VolGroup/lv_root
 resize2fs  /dev/VolGroup/lv_root   
 lsblk
    ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    NAME                        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
    sr0                          11:0    1  1024M  0 rom  
    sda                           8:0    0   500G  0 disk 
        +¦sda1                        8:1    0   500M  0 part /boot
        L¦sda2                        8:2    0 499.5G  0 part 
            +¦VolGroup-lv_root (dm-0) 253:0    0   480G  0 lvm  /
            L¦VolGroup-lv_swap (dm-1) 253:1    0     4G  0 lvm  [SWAP]
    ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
- Check whether the filesystem extended or not with creating a huge file:
 fallocate -l 480G /test_file
- Remove the test file of course:
 rm -rif /test_file