Fully launch 3p-use-ampcontext, and clean up old code

[lannka]

This is the follow up work for #8087

Proposed phases:

• write a simple integration test checks the existence of all documented APIs
• launch in 1% canary, check error logs
• full launch
• clean up code

Since this should be a no behavior change refactoring, it's optional for developers to opt-in and test. @jasti what you think? any channel to bring this up to developer's attention?

[jasti]

@lannka approach seems fine. I suggest we get to the point of launching 1% canary and notify developers in the AMP ads "team" in GH and Slack.

[jasti]

@alanorozco Is this going to finished today or does it need to be moved to the next sprint?

[lannka]

ix experienced an outage after this launching. we under looked the risks and meanwhile our communication wasn't enough to capture such a bug in testing stage.

To prevent this from happening again, we should have a more formal process for launching any changes might potentially affect 3rd parties.

@jasti what you say?
/cc @alanorozco

[lannka]

Tests are added and all issues are addressed.
See #10575 #10628 #10456 #8008 #12333

I'd like to move forward the launch again by starting a communication with all integrated ad networks.

No changes were made to the externally documented APIs. But we do suggest all ad networks to play with our new implementation by turning on the experiment feature flag.

• Go to AMP experiment console page, and toggle the item 3p-use-ampcontext.
• Go to any AMP pages that are integrated with your ad network, and see if everything is working as before. Make sure you tests ad slots that are relying on the context APIs.

However, if your integration relies on the old implementation, e.g. interacting with the APIs using postMessage composed by your code, this launch is a breaking change. Because we changed the postMessage format (to be unified across the whole AMP project), and we don't expect any ad network to really use that. If you're already doing so, you will need to make a change your side to get it fixed. Again, you can follow the above testing instruction to verify.

@jasti could you please forward this message to appropriate working group? The aimed timeline is to launch this 3 weeks later, which will be the 1/23/2018. (Let me know if you have any other suggestion about the timeline.)

[jasti]

@chrisdrexlerlemire-indexexchange @yieldmo-rao @ampproject/ads would you please be able to test the documented APIs before we launch?
An email has also been sent to amp-ads-announce@googlegroups.com group to communicate this change.

[ghost]

Hi @jasti - we'll run some tests and let you know of the results. Appreciate the heads up!

[harquail]

@jasti Yieldmo didn't see any impact of this change on our AMP implementation.
Thanks for letting us know!

[lannka]

Legacy code has been cleaned up: #14787