tech improvement: stop using kiosk-browser APIs

[adghayes]

Overview

Originally, kiosk-browser (i.e. our electron wrapper) was our only way of accessing many system APIs. Now we have backends for every app that do that for us. We want to stop using any kiosk-browser APIs because we want the option of using a more lightweight alternative to electron that simply renders web content. Even if we, for some reason, can't replace kiosk-browser, moving things from kiosk-browser to the backend aligns better with our architectural model.

Apps vary in how much they're using kiosk-browser. Separately, the dev dock uses a few kiosk-browser APIs. The removals, by app, are:

Dev Dock

• Screenshots - uses screenshot and writeFile endpoints. We could simply disable this or provide an alternative.
• Fixture Selection - uses showOpenDialog to pick a file. Most browser replacements would offer this

VxScan

No usage.

VxCentralScan

• Scanner Connection Status - needs to use polling through the backend

VxMarkScan

• Battery Info (tech-improvement: get battery status through backend, not Electron #4533)
• Speech Synthesis
• Rendering ballot to PDF

VxMark

• Battery Info (tech-improvement: get battery status through backend, not Electron #4533)
• Accessible Controller Connection Status (VxMark)
• Speech Synthesis
• Rendering & printing ballot to PDF
• Printer Status

VxAdmin

• Report Printing - uses kiosk.print and file system endpoints (tech-improvement: transition report printing to backend in VxAdmin #4532)
• Printer Status (tech-improvement: transition report printing to backend in VxAdmin #4532)
• Custom Location Saving - uses showSaveDialog (we could also just axe this)
• Custom Select File - uses showOpenDialog

Miscellaneous

A drop-in replacement for kiosk-browser would also have to handle:

• logging to console, unless all logging is moved to backend
• quit? A shortcut to close the frontend in VxDev

We will gradually move away from these endpoints as our work touches them. In the meantime, the path is cleared on VxScan (and pretty much on VxCentralScan too) to begin experimenting with a replacement. The replacement would have to meet other production image and security requirements that are not listed here, but it's likely that overall a slimmer replacement would be easier to work with than Electron.