Create a loading indicator for comments

[ioanarusiczki]

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As discussed https://github.com/mozilla/addons-code-manager/issues/114#issuecomment-547967305

STR:

1. Load a Browser page which contains reviewer comments https://code.addons-dev.allizom.org/en-US/browse/390151/versions/1688302/?messageUid=0f2fa4cbd8354a6fb1020f5f7ec2369e&path=mozilla-recommendation.json
2. Observe the NavBar while the page is loading.

Expected result: A loading indicator is available for Comments and Comment Summary.

Actual result: Comments and Comment Summary appear with a small delay.

Notes: This issue is reproducible with the reviewer comments too. Same fix should be applied but perhaps after https://github.com/mozilla/addons-code-manager/issues/114 lands.

the Nav Bar

the Comments

┆Issue is synchronized with this Jira Task

[kumar303]

@ioanarusiczki ah, I also noticed that the API could be faster here. I filed https://github.com/mozilla/addons/issues/7100

Here are some thoughts on the loading indicator

• It's currently impossible to know if a version has saved comments or not before making an API request for those comments. Thus, it wouldn't make sense (or would it?) to show a loading indicator for the case where the version does not have comments. This needs some thought.
• Maybe there is a way to patch the initial get version API response to indicate whether saved comments exist or not for the current user. This would solve the problem above.

[ioanarusiczki]

@kumar303 Indeed, I see that the response timings increase with the number of comments made.

12 comments from AMO dev

12 comments from Postman - the API response :