Display correct quota info in supported browsers.

[dero]

Summary

Issue: The information displayed on Manage Downloads page is incorrect (hardcoded).

Solution: Use the StorageManager.estimate method to retrieve correct values for the quota and used space in browsers that support it.

Checklist

• My pull request is addressing an open issue (please create one otherwise).
• My code is tested and passes existing tests.
• My code follows the Contributing Guidelines (updates are often made to the guidelines, check it out periodically).

[derekherman]

Works as expected, but has exposed a bug. Which is that the delete all button doesn't actually delete the video from storage or at least not from the calculations.

[dero]

Thanks, @derekherman – I'm now (1343425) dispatching an event in our IDB connection anytime the data in the database change (new data is written or existing data get removed). The storage quota message subscribes to those event and redraws reactively.

Observing a download operation is a good example, see screencast.

2021-03-19_10-54-39.mp4

(It also shows how write operations sometimes need a second to actually finish writing the data to the database after the download is paused. That is expected due to the async IDB design.)

[derekherman]

@delawski really great addition to the PR. However, I was referring to how those numbers responds to a delete all event. Here's a video.

Screen.Recording.2021-03-19.at.5.37.42.PM.mov

[dero]

@derekherman Thanks for the screencast – delete all should work and report the change. It works in my testing.

2021-03-20_08-57-56.mp4

The issue you're seeing is likely due to you testing in Incognito. See related bug in Chromium bug tracker. I'd say private browsing is going to mess up the experience in strange ways in multiple browsers, for example Firefox doesn't allow IDB access at all in their Private mode.