= Background information
`media-list` doesn't include the exact image URLs that will be requested by `mobile-html`, only the original file name. This makes it difficult to save a page for offline without knowing the internal implementation details of `mobile-html` and how to construct the thumbnail URL at the correct size.
= What
Add the exact image URLs to `mobile-html-offline-resources`
= How
Pull the `data-srcset` and `data-src` from lazily loaded image spans and `src` and `srcset` from all image tags.
I'd imagine a structure along the lines of:
```
images: [ // list of all images
{
srcset: [
{src: //upload.wikimedia.org/wikipedia/commons/thumb/6/69/Dog_morphological_variation.png/640px-Dog_morphological_variation.png, scale: 1x}, // import src as 1x if 1x isn't in srcset
{src: //upload.wikimedia.org/wikipedia/commons/thumb/6/69/Dog_morphological_variation.png/640px-Dog_morphological_variation.png, scale: 1.5x}
]
},
{
srcset: [
{src: //upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Dog_anatomy_lateral_skeleton_view.jpg/640px-Dog_anatomy_lateral_skeleton_view.jpg, scale: 1x},
{src: //upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Dog_anatomy_lateral_skeleton_view.jpg/960px-Dog_anatomy_lateral_skeleton_view.jpg, scale: 1.5x},
{src: //upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Dog_anatomy_lateral_skeleton_view.jpg/1280px-Dog_anatomy_lateral_skeleton_view.jpg, scale: 2x}
]
}
]
```