Recalculate network status when navigation ends

[xiaochen-z]

Fix #214.

After some investigations, it seems adding the recalculation step in set the ongoing navigation algorithm makes the most sense.

The only similar feature in the current standard is the navigation API, which has two promises. Their resolution or rejection are done when certain navigation events are fired. See:

• resolve the finished promise
• reject the finished promise

However, these promises are only relevant for navigations that are intercepted by the navigation API. When a cross-site navigation is not intercepted by the navigation API, no resolution or rejection steps are run on the promises because they will disappear together with the current document, as stated in the explainer (See the last paragraph in the linked section):

And if they are non-intercepted cross-document navigations, then the returned promises, along with the entire JavaScript global environment, will disappear as the current document gets unloaded.

So simply adding the recalculation steps to where navigation API resolves its promises does not work as the cross-document navigation cases are not handled.

In the implementation, the network status recalculation is done whenever a navigation ends. In other words, when a frame changes from having an ongoing navigation, to not having an ongoing navigation. So it appears set the ongoing navigation algorithm is the best place to add this step because it is the centralized place where the ongoing navigation state is changed.

There was a previous PR that briefly touched on how to spec this, see this comment.

---

Preview | Diff

[xiaochen-z]

+@blu25 for the first scan. Thank you.

[blu25]

LGTM

[xiaochen-z]

• @domfarolino for review. I've added some findings in the PR description since I last discussed where to spec this with you. Thanks!