For #8125 - Send top sites count with metrics ping

[ekager]

Pull Request checklist

• Tests: This PR includes thorough tests or an explanation of why it does not
• Screenshots: This PR includes screenshots or GIFs of the changes made or an explanation of why it does not
• Accessibility: The code in this PR follows accessibility best practices or does not include any user facing features. In addition, it includes a screenshot of a successful accessibility scan to ensure no new defects are added to the product.

After merge

• Milestone: Make sure issues finished by this pull request are added to the milestone of the version currently in development.

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3. click on the "Fenix - assemble" task, then click "Run Artifacts".
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[codecov-io]

Codecov Report

Merging #9556 into master will decrease coverage by <.01%.
The diff coverage is 66.66%.

@@             Coverage Diff              @@
##             master    #9556      +/-   ##
============================================
- Coverage     19.41%   19.41%   -0.01%     
  Complexity      519      519              
============================================
  Files           335      335              
  Lines         13451    13472      +21     
  Branches       1791     1793       +2     
============================================
+ Hits           2611     2615       +4     
- Misses        10616    10633      +17     
  Partials        224      224

Impacted Files	Coverage Δ	Complexity Δ
...c/main/java/org/mozilla/fenix/home/HomeFragment.kt	0% <0%> (ø)	0 <0> (ø)	⬇️
...la/fenix/components/metrics/GleanMetricsService.kt	9.22% <100%> (+0.27%)	3 <0> (ø)	⬇️
.../src/main/java/org/mozilla/fenix/utils/Settings.kt	76.1% <100%> (+0.24%)	30 <0> (ø)	⬇️
...n/java/org/mozilla/fenix/IntentReceiverActivity.kt	0% <0%> (ø)	0% <0%> (ø)	⬇️

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[ekager]

Request for data collection review form

All questions are mandatory. You must receive review from a data steward peer on your responses to these questions before shipping new data collection.

1. What questions will you answer with this data?

Does this user have any top sites and how many do they have?

2. Why does Mozilla need to answer these questions? Are there benefits for users? Do we need this information to address product or business requirements?

We've seen a correlation between startup time and the number of top sites in local testing and knowing quantities will better inform both technical and UX-based solutions.

3. What alternative methods did you consider to answer these questions? Why were they not sufficient?

Local testing for performance, but knowing how many top sites real users have will help inform the teams for performance investigations.

4. Can current instrumentation answer these questions?

No, top sites are a new feature.

5. List all proposed measurements and indicate the category of data collection for each measurement, using the Firefox data collection categories found on the Mozilla wiki.

Note that the data steward reviewing your request will characterize your data collection based on the highest (and most sensitive) category.

Measurement Description	Data Collection Category	Tracking Bug #
top sites count	Category 2	https://github.com//issues/8125
user has top sites	Category 2	https://github.com//issues/8125

6. How long will this data be collected? Choose one of the following:
   This is scoped to a time-limited experiment/project until date 09-01-2020.

7. What populations will you measure?
   All release, beta, and nightly users with telemetry enabled.

8. If this data collection is default on, what is the opt-out mechanism for users?
   Users can opt of of data collection by disabling Usage and technical data from Settings -> Data collection.

9. Please provide a general description of how you will analyze this data.
   Glean / Amplitude

10. Where do you intend to share the results of your analysis?
    Only on Glean, Amplitude and with mobile teams.

11. Is there a third-party tool (i.e. not Telemetry) that you are proposing to use for this data collection?
    No.

[ekager]

cc @boek this is ready for review + data review :)

[boek]

Data Review Form (to be filled by Data Stewards)

1. Is there or will there be documentation that describes the schema for the ultimate data set in a public, complete, and accurate way?
   Yes, metrics.yaml and metrics.md

2. Is there a control mechanism that allows the user to turn the data collection on and off?
   Yes, under data controls

3. If the request is for permanent data collection, is there someone who will monitor the data over time?
   Has expiry

4. Using the category system of data types on the Mozilla wiki, what collection type of data do the requested measurements fall under?
   Type 2

5. Is the data collection request for default-on or default-off?
   Default on

6. Does the instrumentation include the addition of any new identifiers (whether anonymous or otherwise; e.g., username, random IDs, etc. See the appendix for more details)?
   No

7. Is the data collection covered by the existing Firefox privacy notice?
   Yes

8. Does there need to be a check-in in the future to determine whether to renew the data?
   Has expiry

9. Does the data collection use a third-party collection tool?
   no

[boek]

Should we just use the topSitesSize intPreference that you added in Settings.kt here?