Gather preliminary numbers for cold start to homescreen

[mcomella]

Why/User Benefit/User Problem

We want to know how Fenix compares to Fennec 68 currently in order to inform priorities: see https://github.com/mozilla-mobile/perf-frontend-issues/issues/30 for details.

This bug is to gather preliminary timing numbers for cold start to homescreen, one of our P1 release criteria. These numbers can be retrieved in a lightweight fashion – i.e. they don't need to be in a robust system like Nimbledroid.

Impact

If we don't do this, we won't have data to inform our decision in #30.

Acceptance Criteria (how do I know when I’m done?)

• Gathered numbers and shared results with team
• Steps taken to retrieve numbers have been documented

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hawkinsw may already have these numbers from the measurement system on his desk – check with hawkinsw before proceeding.

[mcomella]

Closing because I believe this is completed. Please reopen if you disagree.