Fix visualize CVPixelBuffer command
Fix visualize CVPixelBuffer command

Summary:
Fixes two issues:

1. Candidate function not viable
2. Redefinition of persistent varible

Differential Revision: D35440520

fbshipit-source-id: 1d5091b88a9776e99a0da91d457feba51bdeb2ed

facebook/chisel,facebook/chisel,facebook/chisel