Cache favicons (to prevent fetching each time Brave is reloaded)

[luixxiul]

Describe the issue you encountered: If favicons of bookmarks become 404, the favicons are also gone, which makes it difficult to notice that the bookmark is there, until #2075 is fixed. Also if a user starts Brave offline, no favicon will be displayed.

Expected behavior: When the user visit the site, Brave should store favicons in the Base64 format and replace them with it, and it should check if the favicon needs updating when the user revisits the site.

• Brave Version: 0.11.1

[luixxiul]

Also "clear site data" option from menubar should remove the favicon cache too.

[bsclifton]

Caching would also be good because there is a delay in the bookmarks toolbar... for example, when you open a folder that has links. The delay is might only be 200 milliseconds before the image shows but it's noticeable.

[bbondy]

@bsclifton someone complained about that on twitter recently. cc @BrendanEich

[bsclifton]

For content pages like about:bookmarks, images are cached. However, images that are in the browser do not seem to be caching... like favicons in the bookmarks toolbar and the ones from the back/forward nav buttons (ex: stuff you can see when you load the shift+F8 dev tools).

When discussing with @bridiver, it seems that these are not using a public context when fetching, so it doesn't get cached. @bridiver did you have any info to add?

[bsclifton]

+1 from #5840; Assigned milestone

[bridiver]

I can bring in the history component from chromium

[bsclifton]

@bridiver would this help with content loaded in a private context? ex: our main UI?

[luixxiul]

I would be banned due to potential DOS attack:

If it is not easy to cache favicons for now, why don't we limit the maximum number of retry to fetch them, or prevent the browser from retrying to do so if the page is reloaded automatically?

[luixxiul]

Also: requesting favicons each time on reload can be a strong indicator of the browser. It might be stronger than fingerprinting. CC @diracdeltas

[diracdeltas]

favicon cache seems useful. it should be cleared at least whenever the user clears history.

we should be careful not to persist favicons from private tabs to disk. this was an issue previously before we changed the favicon context to non-persistent.

[bsclifton]

Closing as wontfix as this will be addressed with Brave Core (coming soon). This is the new Chromium based UI which replaces the Muon based UI we use currently