[metrics_center] Remove github dependency

[CaseyHillers]

flutter/cocoon depends on metrics_center. Metrics center cannot be upgraded past version 7 because of dependency issues.

Instead, remove the dependency and require Cocoon to pass the commit timestamp.

flutter/flutter#79467

Pre-launch Checklist

• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• I read and followed the [Flutter Style Guide].
• I listed at least one issue that this PR fixes in the description above.
• I added new tests to check the change I am making or feature I am adding, or Hixie said the PR is test-exempt.
• I updated pubspec.yaml with an appropriate new version according to the [pub versioning philosophy].
• I updated CHANGELOG.md to add a description of the change.
• I updated/added relevant documentation (doc comments with ///).
• I signed the [CLA].
• All existing and new tests are passing.

[CaseyHillers]

30dced1 is the commit with the changes

[keyonghan]

Do we know what other sources pointing to metrics center? Cocoon is one, I notice engine uses it as well: https://devops-console-oss.corp.google.com/flutter/engine/+/master:testing/benchmark/bin/parse_and_send.dart;l=71.
We need to make sure its dependents do not fail.

[CaseyHillers]

Thanks Keyong for pointing this out! Flutter code search shows only results in flutter/cocoon and flutter/engine. Both are pinned to 0.0.9

My plan was to update the version here, then patch Cocoon to be compatible with 0.1.0.

For flutter/engine, I'll need to:

1. Update parse_and_send.dart to take commit timestamp
2. Update recipe to pass commit timestamp
3. Patch metrics_center to 0.1.0

SG?

[CaseyHillers]

Tests are failing as I should be using a Utc datetime instead of the local time

[keyonghan]

Thanks Keyong for pointing this out! Flutter code search shows only results in flutter/cocoon and flutter/engine. Both are pinned to 0.0.9

My plan was to update the version here, then patch Cocoon to be compatible with 0.1.0.

For flutter/engine, I'll need to:

1. Update parse_and_send.dart to take commit timestamp
2. Update recipe to pass commit timestamp
3. Patch metrics_center to 0.1.0

SG?

This makes sense. Thanks.

[keyonghan]

LGTM with the test fixed.

[CaseyHillers]

@keyonghan I switched the timestamps to be explicitly stored as UTC. Before they were based on the local time of the server it was run in. Is this okay?

[keyonghan]

Is it easy to fix from test side rather than enforcing the UTC from code here?

[CaseyHillers]

Okay switched back to previous functionality. This will cause issues if there are instances distributed globally running this logic.

[keyonghan]

After revisiting the code, I agree that we need to enforce the timezone to be consistent.
But I guess our current logic is based on PST (could you please double check?). If so, let's enforce PST instead.

[CaseyHillers]

For Cocoon, the GAE instance is in us-central. I presume the engine use case is running on LUCI, which has more variance.

I think UTC is the safest option to default to the data would only jump forward in time when this change occurs (unless there are instances in EMEA/Asia). SG?

[keyonghan]

Just validated existing bucket is using UTC. Sounds good to me.

[keyonghan]

LGTM