For #12287: Add Synced Tabs to Tabs Tray

[jonalmeida]

The feature is put behind a feature flag from the Secret Settings. Might be easier to review per commit.

Abstract design link to verify against.

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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[jonalmeida]

The parts I'm most unsure of are the navigation graph additions.

[codecov-commenter]

Codecov Report

Merging #13893 into master will increase coverage by 0.13%.
The diff coverage is 49.60%.

@@             Coverage Diff              @@
##             master   #13893      +/-   ##
============================================
+ Coverage     29.76%   29.90%   +0.13%     
- Complexity     1117     1125       +8     
============================================
  Files           422      425       +3     
  Lines         17204    17293      +89     
  Branches       2232     2241       +9     
============================================
+ Hits           5121     5171      +50     
- Misses        11709    11747      +38     
- Partials        374      375       +1     

Impacted Files	Coverage Δ	Complexity Δ
...pp/src/main/java/org/mozilla/fenix/HomeActivity.kt	6.58% <0.00%> (-0.03%)	11.00 <0.00> (ø)
...org/mozilla/fenix/components/BackgroundServices.kt	23.61% <0.00%> (+0.32%)	0.00 <0.00> (ø)
...lla/fenix/components/toolbar/DefaultToolbarMenu.kt	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...p/src/main/java/org/mozilla/fenix/home/HomeMenu.kt	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...g/mozilla/fenix/settings/SecretSettingsFragment.kt	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
.../fenix/settings/account/AccountSettingsFragment.kt	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
.../java/org/mozilla/fenix/sync/SyncedTabsFragment.kt	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...org/mozilla/fenix/tabtray/TabTrayDialogFragment.kt	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...main/java/org/mozilla/fenix/tabtray/TabTrayView.kt	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...in/java/org/mozilla/fenix/sync/SyncedTabsLayout.kt	11.11% <14.28%> (-18.16%)	0.00 <0.00> (ø)
... and 14 more

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[ekager]

Pulled this down and looks good overall, but I noticed a few things:

1. Do we want this to show in the private tab in the tabs tray?
2. We probably want to hide this in multiselect mode like we do for the save to collection button because otherwise it looks a bit strange?
   
3. When opening the tabs tray with synced tabs enabled and 1 open tab, it seems to jump to the synced tabs section and opens at an awkward point in the list.
   
4. Sometimes (can't repro 100%) it even opens further down on the synced tabs list and I would have to scroll way up to see open tabs. When I swipe up to try to scroll, it closes. Got a video from after it opened.
   

Moving this into it's own Tabs Tray Tab (phew mouthful) would likely solve all these problems, so if we decide to move that way (via this comment #12287 (comment) ) we can probably disregard these issues.

cc @topotropic

[jonalmeida]

Thanks for the review; super helpful!

1. Do we want this to show in the private tab in the tabs tray?

We currently don't have it in private tabs similar to the 'Add to collections' button, although I'll leave it up to @topotropic to comment (and to also consider the separate tab idea that Sorin mentioned).

2. We probably want to hide this in multiselect mode like we do for the save to collection button because otherwise it looks a bit strange?

Fixed! Check out the last commit that addresses the review comments.

3. When opening the tabs tray with synced tabs enabled and 1 open tab, it seems to jump to the synced tabs section and opens at an awkward point in the list.
4. Sometimes (can't repro 100%) it even opens further down on the synced tabs list and I would have to scroll way up to see open tabs. When I swipe up to try to scroll, it closes. Got a video from after it opened.

These two are related and are a side-effect to how the tabs tray scrolls to the selected tab. The hacky approach that we currently have (calculate the index based on the adapter size), does not consider that the adapter is loaded async and we need to scroll when all the adapters are complete.

I've filed #13905 to address this and added it as a blocker for removing the feature flag.

Moving this into it's own Tabs Tray Tab (phew mouthful) would likely solve all these problems, so if we decide to move that way (via this comment #12287 (comment) ) we can probably disregard these issues.

Yes! I'd really like us to look into this but I don't think it'll block us from landing this change.

[ekager]

Sounds good, I don't think the UX questions/bugs should block the flagged feature!