Support importing tabs from legacy Brave (Muon)

[bbondy]

Test plan

See brave/brave-core#981

Description

This would make migration almost completely painless.

[garrettr]

I'm working on importing pinned sites right now and have run into a design problem that doesn't have an obvious solution. The problem is b-l and b-c handle pinned sites differently: pinned sites are global in b-l, but they are per-window in b-c.

Options for how to handle this:

1. During import, inject pinned sites into each imported window at the beginning of the tab strip.
   • Pros: user gets identical tab layout in transition from b-l to b-c
   • Cons: this is cosmetic at best. The tabs will all be distinct, and their state will not be maintained across windows as it is in b-l, because that is not how pinned sites work in b-c. This might annoy users who are initially expecting the old behavior, to find only a mirage.
2. Create a new window to hold just the pinned sites.
3. Something else I haven't thought of?

[bsclifton]

How about option 3 - import the pinned tabs ONLY to the FIRST window 😄

[bsclifton]

Fixed with brave/brave-core#981 😄

I renamed this issue (so it reflects that import only happens for Muon Brave) and created a more general issue #2309

[LaurenWags]

@garrettr @bsclifton what's the expected result if you had pages like 'about:brave' or 'about:preferences#payments' opened in muon? When those pages are imported to b-c I see the below. (note, about:history seems to have correctly migrated to brave://history)

[LaurenWags]

@garrettr @bsclifton if I import a muon profile with a bunch of tabs (think 4 windows approx 100 tabs in each window), I beachball for a few seconds and then the fans on my mac start to kick on. it looks like we're loading all tabs simultaneously after import. Subsequent launches of b-c seem to be ok (no fan action) and when I click on a tab that's when it loads. Is this expected? cc @kjozwiak

[bsclifton]

Per discussion, some waiting is OK- but the import should be happening async (UI should be responsive, etc)

@LaurenWags has logged #2374 to address the issue 😄 👍

[btlechowski]

Verification Passed on

Brave	0.57.16 Chromium: 71.0.3578.80 (Official Build) (64-bit)
Revision	2ac50e7249fbd55e6f517a28131605c9fb9fe897-refs/branch-heads/3578@{#860}
OS	Windows 7

Migrated from muon v0.25.201

• normal tab was imported
• private tab was ignored
• private tab with tor was ignored
• session tab was imported as normal tab
• multi windows were imported.
• multi tabs were imported, but slow with 20+ tabs (beachball/perf hit after importing many tabs from muon #2374). The more the tabs the worse it is as all tabs are loaded concurrently.
• pinned tabs were imported as pinned tab

Verified passed with

Brave	0.57.16 Chromium: 71.0.3578.80 (Official Build) (64-bit)
Revision	2ac50e7249fbd55e6f517a28131605c9fb9fe897-refs/branch-heads/3578@{#860}
OS	Mac OS X

• Verified test plan from Import open windows and tabs from legacy Brave brave-core#981
• Verified pinned tabs are only in one window
• Encountered and logged beachball/perf hit after importing many tabs from muon #2374 for when you import many tabs as noted in Support importing tabs from legacy Brave (Muon) #998 (comment)
• Verified private and tor tabs were not imported.
• Verified session tabs imported as normal tabs.
• Verified multiple tabs/windows imported.

Verification passed on

Brave	0.57.17 Chromium: 71.0.3578.80 (Official Build) (64-bit)
Revision	2ac50e7249fbd55e6f517a28131605c9fb9fe897-refs/branch-heads/3578@{#860}
OS	Linux

All import functions on Linux is done via manual import as auto migration is not supported

• Verified tabs are imported into a new window
• Verified bookmarks are imported
• Verified stats are imported
• Verified history is imported
• Verified saved passwords are imported
• Verified Cookies and logged in session are imported
• Verified session tabs are imported as normal tabs
• Verified private/tor tabs are not imported