It looks like we could run into this when there is a network change after sign-in before merge session finishes.

Hit this occasionally:
====
[89546:89546:1101/132528.074802:FATAL:oauth2_login_manager.cc(210)] Check failed: !login_verifier_.get().
#0 0x7f561f00876f base::debug::StackTrace::StackTrace()
#1 0x7f561ef3a99b logging::LogMessage::~LogMessage() 
#2 0x56492b74163e chromeos::OAuth2LoginManager::VerifySessionCookies()                                                                                                              #3 0x56492b74144c chromeos::OAuth2LoginManager::RestoreSessionFromSavedTokens()
#4 0x56492b7412bd chromeos::OAuth2LoginManager::ContinueSessionRestore()
#5 0x56492b739467 chromeos::UserSessionManager::OnNetworkChanged()
#6 0x7f561da46152 base::ObserverListThreadSafe<>::NotifyWrapper()
#7 0x7f561da46650 _ZN4base8internal7InvokerINS0_9BindStateIMNS_22ObserverListThreadSafeIN3net12CertDatabase8ObserverEEEFvPS6_RKNS7_16NotificationDataEEJ13scoped_refptrIS7_ES8_S9_EE
EFvvEE7RunOnceEPNS0_13BindStateBaseE
#8 0x7f561ef1dc7a base::debug::TaskAnnotator::RunTask()
#9 0x7f561ef493df base::MessageLoop::RunTask()
#10 0x7f561ef497d3 base::MessageLoop::DoWork()
#11 0x7f561f02bf79 base::MessagePumpLibevent::Run()
#12 0x7f561ef48f84 base::MessageLoop::Run()
#13 0x7f561ef7bf29 base::RunLoop::Run()
#14 0x56492bc0b1ed ChromeBrowserMainParts::MainMessageLoopRun()