We collected slow reports from users facing janks and found that the function mentioned above is taking too much time on the main thread, potentially causing janks.
The issue can be found in reports:

Go to crash/ReportID to view the traces.
1def0ff4a6b2e7c3  - 1821 ms

The stack traces that were hit the most:

           url::CanonicalizeScheme(char const*, url::Component const&, url::CanonOutputT<char>*, url::Component*)
           bool url::(anonymous namespace)::DoCanonicalizeStandardURL<char, unsigned char>(url::URLComponentSource<char> const&, url::Parsed const&, url::SchemeType, url::CharsetConverter*, url::CanonOutputT<char>*, url::Parsed*)
           url::CanonicalizeStandardURL(char const*, int, url::Parsed const&, url::SchemeType, url::CharsetConverter*, url::CanonOutputT<char>*, url::Parsed*)
           bool url::(anonymous namespace)::DoCanonicalize<char>(char const*, int, bool, url::(anonymous namespace)::WhitespaceRemovalPolicy, url::CharsetConverter*, url::CanonOutputT<char>*, url::Parsed*)
           url::Canonicalize(char const*, int, bool, url::CharsetConverter*, url::CanonOutputT<char>*, url::Parsed*)
           GURL::GURL(base::BasicStringPiece<std::__ndk1::basic_string<char, std::__ndk1::char_traits<char>, std::__ndk1::allocator<char> > >)
           sync_sessions::FaviconCache::UpdateMappingsFromForeignTab(sync_pb::SessionTab const&, base::Time)
           sync_sessions::(anonymous namespace)::FactoryImpl::OnReadAllMetadata()
           base::OnceCallback<void (std::__ndk1::unique_ptr<media::AudioDecoder, std::__ndk1::default_delete<media::AudioDecoder> >, std::__ndk1::unique_ptr<media::DecryptingDemuxerStream, std::__ndk1::default_delete<media::DecryptingDemuxerStream> >)>::Run(std::__ndk1::unique_ptr<media::AudioDecoder, std::__ndk1::default_delete<media::AudioDecoder> >, std::__ndk1::unique_ptr<media::DecryptingDemuxerStream, std::__ndk1::default_delete<media::DecryptingDemuxerStream> >) &&
           syncer::ModelTypeStoreImpl::ReadAllMetadataDone(base::OnceCallback<void (base::Optional<syncer::ModelError> const&, std::__ndk1::unique_ptr<syncer::MetadataBatch, std::__ndk1::default_delete<syncer::MetadataBatch> >)>, std::__ndk1::unique_ptr<syncer::MetadataBatch, std::__ndk1::default_delete<syncer::MetadataBatch> >, base::Optional<syncer::ModelError> const&)
           base::OnceCallback<void (std::__ndk1::basic_string<char, std::__ndk1::char_traits<char>, std::__ndk1::allocator<char> > const&)>::Run(std::__ndk1::basic_string<char, std::__ndk1::char_traits<char>, std::__ndk1::allocator<char> > const&) &&
           base::(anonymous namespace)::PostTaskAndReplyRelay::RunReply(base::(anonymous namespace)::PostTaskAndReplyRelay)
           base::debug::TaskAnnotator::RunTask(char const*, base::PendingTask*)
           base::MessageLoop::RunTask(base::PendingTask*)
           base::MessageLoop::DoWork()
           base::MessagePumpForUI::OnNonDelayedLooperCallback()
           base::(anonymous namespace)::NonDelayedLooperCallback(int, int, void*)


        std::__ndk1::vector<sessions::SerializedNavigationEntry, std::__ndk1::allocator<sessions::SerializedNavigationEntry> >::__swap_out_circular_buffer(std::__ndk1::__split_buffer<sessions::SerializedNavigationEntry, std::__ndk1::allocator<sessions::SerializedNavigationEntry>&>&)
           void std::__ndk1::vector<sessions::SerializedNavigationEntry, std::__ndk1::allocator<sessions::SerializedNavigationEntry> >::__push_back_slow_path<sessions::SerializedNavigationEntry>(sessions::SerializedNavigationEntry&&)
           sync_sessions::SetSessionTabFromSyncData(sync_pb::SessionTab const&, base::Time, sessions::SessionTab*)
           sync_sessions::UpdateTrackerWithSpecifics(sync_pb::SessionSpecifics const&, base::Time, sync_sessions::SyncedSessionTracker*)

           sync_sessions::(anonymous namespace)::FactoryImpl::OnReadAllMetadata()

           syncer::ModelTypeStoreImpl::ReadAllMetadataDone(base::OnceCallback<void (base::Optional<syncer::ModelError> const&, std::__ndk1::unique_ptr<syncer::MetadataBatch, std::__ndk1::default_delete<syncer::MetadataBatch> >)>, std::__ndk1::unique_ptr<syncer::MetadataBatch, std::__ndk1::default_delete<syncer::MetadataBatch> >, base::Optional<syncer::ModelError> const&)
           base::OnceCallback<void (std::__ndk1::basic_string<char, std::__ndk1::char_traits<char>, std::__ndk1::allocator<char> > const&)>::Run(std::__ndk1::basic_string<char, std::__ndk1::char_traits<char>, std::__ndk1::allocator<char> > const&) &&
           base::(anonymous namespace)::PostTaskAndReplyRelay::RunReply(base::(anonymous namespace)::PostTaskAndReplyRelay)
           void base::internal::FunctorTraits<void (*)(base::(anonymous namespace)::PostTaskAndReplyRelay), void>::Invoke<void (*)(base::(anonymous namespace)::PostTaskAndReplyRelay), base::(anonymous namespace)::PostTaskAndReplyRelay>(void (*&&)(base::(anonymous namespace)::PostTaskAndReplyRelay), base::(anonymous namespace)::PostTaskAndReplyRelay&&)
           base::debug::TaskAnnotator::RunTask(char const*, base::PendingTask*)
           base::MessageLoop::RunTask(base::PendingTask*)
           base::MessageLoop::DoWork()
           base::MessagePumpForUI::OnNonDelayedLooperCallback()
           base::(anonymous namespace)::NonDelayedLooperCallback(int, int, void*)