For #20017: a cold main session restore to measure_start_up

[mcomella]

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.

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[codecov-commenter]

Codecov Report

Merging #20020 (fa9d0a9) into master (dfc5628) will increase coverage by 4.08%.
The diff coverage is 31.58%.

@@             Coverage Diff              @@
##             master   #20020      +/-   ##
============================================
+ Coverage     32.83%   36.92%   +4.08%     
- Complexity     1382     1645     +263     
============================================
  Files           461      542      +81     
  Lines         19425    21055    +1630     
  Branches       2712     3154     +442     
============================================
+ Hits           6379     7774    +1395     
+ Misses        12510    12379     -131     
- Partials        536      902     +366     

Impacted Files	Coverage Δ
...in/java/org/mozilla/fenix/AppRequestInterceptor.kt	93.02% <0.00%> (ø)
.../src/main/java/org/mozilla/fenix/SecureFragment.kt	0.00% <0.00%> (ø)
...g/mozilla/fenix/addons/AddonsManagementFragment.kt	6.62% <0.00%> (-0.19%)	⬇️
...illa/fenix/addons/InstalledAddonDetailsFragment.kt	0.00% <0.00%> (ø)
...fenix/android/DefaultActivityLifecycleCallbacks.kt	0.00% <0.00%> (ø)
.../mozilla/fenix/autofill/AutofillConfirmActivity.kt	0.00% <0.00%> (ø)
...g/mozilla/fenix/autofill/AutofillSearchActivity.kt	0.00% <0.00%> (ø)
...java/org/mozilla/fenix/autofill/AutofillService.kt	0.00% <0.00%> (ø)
...g/mozilla/fenix/autofill/AutofillUnlockActivity.kt	0.00% <0.00%> (ø)
...lla/fenix/browser/CustomTabContextMenuCandidate.kt	0.00% <0.00%> (ø)
... and 411 more

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[MarcLeclair]

Works for me, looks good to me. However , i wonder if the cold_main_restore need to mention we need to have a website open for the test case @mcomella (I approved since it works and everything is fine)

[mcomella]

Works for me, looks good to me. However , i wonder if the cold_main_restore need to mention we need to have a website open for the test case @mcomella (I approved since it works and everything is fine)

@MarcLeclair I do mention this in stdout when you run it. Also, the PageStart == 2 assertion should trigger if you don't have a tab open (though the error message there isn't great if you don't read the stdout). Do you think this is sufficient?

[mcomella]

Only changed .py so let's rerun.