DbWrapper deprecation

[tropicadri]

Fixes #2801

Changes in workbox-expiration to use idb and deleting DBWrapper.

[jeffposnick]

Thanks! This all looks a lot cleaner, and I'm glad we were able to drop so much old code.

I just had the one small comment inline.

[jeffposnick]

I'm curious as to why it's this? instead of this. When would this not be defined?

[tropicadri]

Glad you asked, I meant to ask you about that, we call the method to upgradeDB in tests, for example: https://github.com/GoogleChrome/workbox/blob/v6/test/workbox-expiration/sw/test-CacheTimestampsModel.mjs#L16, and that is when this would not be defined. I am not sure if this is still the correct way to do this tests, because the test would be the one creating the IDB because it is opened before each test, maybe we should refactor the tests to open the DB only in the test cases that needs it and only by passing the name?

[jeffposnick]

Hmmm, that's interesting.

I don't think most of the tests end up ever triggering the IDB upgrade flow, do they? Can we just leave out onupgradeneeded from when we call openDB() in our tests?

I think would be cleaner than having a situation in which we need to use this? in the non-test code.

[tropicadri]

Turns out my approach also wouldn't work, so I sort of separated the dbupgrade and the deleting of old dbs and that seems to work, let me know what you think. Thank you!

[jeffposnick]

Hmmm, that's interesting.

I don't think most of the tests end up ever triggering the IDB upgrade flow, do they? Can we just leave out onupgradeneeded from when we call openDB() in our tests?

I think would be cleaner than having a situation in which we need to use this? in the non-test code.

[jeffposnick]

@tropicadri pointed out that onupgradeneeded always runs when going from the initial empty IDB state to an initial IDB instance (not just when going from an initial IDB instance to a new one), so forget what I mentioned about leaving out onupgradeneeded.

As discussed, moving the call to openDB() to run later in the test suite makes the most sense.