(minor) Inconsistent format of screenshot-thumbnails and final-screenshot

[alekseykulikov]

What is the current behavior?

It's a minor inconsistency, but screenshot-thumbnails and final-screenshot have the same type of data but in different format.

{
  "screenshot-thumbnails": {
     "details": {
       "items": [
          {
            "timing": 3335,
            "timestamp": 7104511246,
            "data": "/9j/4AAQSkZJRgABAQAAAQABAAD..."
          }
        ]
     }
  },
  "final-screenshot": {
     "details": {
        "type": "screenshot",
        "timestamp": 7104882.46,
        "data": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQ..."
      }
   }
}

What is the expected behavior?

It would be better to have the new final-screenshot in the same format as screenshot-thumbnails:

• data is a valid base64 encoded jpeg (remove data:image/jpeg;base64,)
• timing contains the actual value
• timestamp in the same scale as other timestamps (timestamp * 1000)

Environment Information

• Lighthouse version: 4.0.0

[patrickhulce]

Thanks for pointing this out @alekseykulikov! Unfortunately we already have consumers relying on the format in final-screenshot :/

Maybe we can put this into 5.0...

Based on the review it looks like it started out as the same as our filmstrip but changed formats before landing. @brendankenny do you recall if there was a PSI reason that prompted the switch?

[patrickhulce]

Fixed by #8299