https://cs.chromium.org/chromium/src/chrome/browser/memory/tab_manager.h?l=115

 It might make sense to rename this method to be something like
DiscardTabWithWebContents() so that readers don't assume that either a) it
should only be used by extensions or b) it does some kind of attribution to
extensions.  I'd probably also omit the part about "used by the extensions API"
- method descriptions should typically describe the behavior rather than the
call sites (unless there's a reason to limit the call site, as in cases where we
might say "Only use this if it's attributable to an extension, etc).