Sorry for not being clear. For the Chrome implementation of the secret image, I was thinking that the user would store it locally inside of Google Chrome configuration. E.g. in "chrome://settings" or "chrome://flags", the user sets the secret image (e.g. a photo of their cat or whatever.)
Oops, I was the one being unclear. I was just going off on a tangent about the HTML ones that some banks use. A native one indeed wouldn't have the problem I'm mentioning.