[Chromium] Images cache partitioning doesn't work while a 3p renderer is alive

Looks like images are cached in the renderer and don’t know anything about NIK areas. If we navigate the renderer away (for ex. to example.com to effectively destroy/clear cache) then the image is not found in the cache and refetched properly.

See https://privacytests.org/ image cache test.

Need to figure out how/if blink caches some simple blobs and make sure it supports NetworkIsolationKey-based partitioning there.

Blink indeed have MemoryCache, but it doesn’t support partitioning out of the box. There is an open issue to implement this, but no signs of activity https://bugs.chromium.org/p/chromium/issues/detail?id=1127971.

[goodov]

@goodov what’s the command line QA needs to use?

--enable-features=PartitionBlinkMemoryCache

[goodov]

For QA: nothing should be changed visually, but internal blink memory cache should behave differently for 3p frames. Can we please check the usual browser behavior regarding 3p frames and any frames in general hasn’t changed and everything works as it should? The test plan will look like this:

1. Enable PartitionBlinkMemoryCache feature via command line.
2. Perform various tests from https://dev-pages.brave.software/storage/index.html
3. Perform an SSO authorization, make sure it works without any issues.

We’d like to have a QA approve for a general sanity so we can enable this in nightly.