subclass of syncer::SyncClient should own brave_sync::BraveSyncClient* and implement GetBraveSyncClient

Update brave sync extension api

Suppress BraveSyncServiceImpl

create sync chain

Start sync engine based on brave_sync enabled

Dispatch OnPollSyncCycle and OnNudgeSyncCycle from sync thread to UI thread

Avoid use_transport_only_mode and put poll/nudge delegate into syncer

fake sync_pb::GetUpdateResponse

Adding BookmarksSpecifics

Put back Device record & overrides short/long poll interval

Add GetRecords callback to PollSyncCycleDelegate

Fix OnGetRecords callback triggered on the wrong thread

Apply real records from sync chain

Get rid of sync event observer for nudge/poll delegate
also partial brave commit builder

Complete brave commit & update (CREATE, DELETE, partial UPDATE)
Add MetaInfo to Bookmark protobuf

…ng duplicate records

deprecate all the logic through brave/sync for getting order

launching from legacy sync profile

from legacy sync. Otherwise, previous sync type will be purged.

…atus so

that sync engine only starts after OnSyncReady

also
1. remove unecessary const_cast
2. fix empty order bug in ReCalculateOrder
3. add ScopedPauseObserver to reduce patch

Make sure brave/brave-browser#4551 and
#2471 landed first

brave_sync deps fix

…raveSyncAllowedByFlag()

…NC in chromium

…yncServiceExports => BraveProfileSyncService

…and update corresponding sync nodes

… fix

Remove unused code

…ix GetDisableReasons unittest

Improved processing of GetOrder('2.5.6.3', '2.5.7.8.2')

Simplified GetOrder

Test for improved processing of GetOrder('2.5.6.3', '2.5.7.8.2')

Updated and expanded tests for simplified GetOrder

Resend meta shouldn't use metainfo from node (delete record doesn't have a node)

1. legacy order will still be sent for compatibility
2. legacy order will be used when there is no position_in_parent (legacy sync)
  during applying remote changes

compatibility

1. Patch standardization
2. Apply clang-format

  1. Remvoe weak_ptr for syncer and make sure get_record_cb_ won't get
  called when sync_thread is not running
  2. Remove unnecessary forward declaration

1. Generate fake NIGORI entity when apply update
2. Set dummy encryption key for every update_response

sync protocol like "version" and "UniquePosition", ...etc