jlebel@ could you PTAL?

I can reproduce it sometimes but not all the times. I wonder if there is race condition.
msarda@, do you known if it is a known problem?

Triage ping: Any updates on this?

I was able to reproduce it with this stacktrace:
* thread #1, name = 'CrWebMain', queue = 'com.apple.main-thread', stop reason = breakpoint 7.1
  * frame #0: 0x0000000109922e26 Chromium`::-[SigninInteractionCoordinator addAccountWithAccessPoint:promoAction:presentingViewController:completion:](self=0x0000618000072100, _cmd="addAccountWithAccessPoint:promoAction:presentingViewController:completion:", accessPoint=ACCESS_POINT_UNKNOWN, promoAction=PROMO_ACTION_NO_SIGNIN_PROMO, viewController=0x00007fba9a80b200, completion=(null)) at signin_interaction_coordinator.mm:102
    frame #1: 0x0000000107ae5756 Chromium`::-[MainController showAddAccountFromViewController:](self=0x00007fba97400b10, _cmd="showAddAccountFromViewController:", baseViewController=0x00007fba9a80b200) at main_controller.mm:1583
    frame #2: 0x00000001097b2183 Chromium`::-[BrowserViewController onAddAccount](self=0x00007fba9a80b200, _cmd="onAddAccount") at browser_view_controller.mm:5799
    frame #3: 0x0000000108a8f9a7 Chromium`(anonymous namespace)::AccountConsistencyHandler::ShouldAllowResponse(this=0x000061c00025aa90, response=0x0000618000224ec0, for_main_frame=true) at account_consistency_service.mm:122
    frame #4: 0x00000001087578a4 Chromium`web::WebStateImpl::ShouldAllowResponse(this=0x00007fba9cd2e980, response=0x0000618000224ec0, for_main_frame=true) at web_state_impl.mm:510
    frame #5: 0x00000001087c8ac6 Chromium`::-[CRWWebController webView:decidePolicyForNavigationResponse:decisionHandler:](self=0x00007fba9cd2eb40, _cmd="webView:decidePolicyForNavigationResponse:decisionHandler:", webView=0x00007fbaa1892a00, navigationResponse=0x00007fba9cb2b540, handler=0x000000011ab4500f)(WKNavigationResponsePolicy)) at crw_web_controller.mm:4344
    frame #6: 0x000000011ab44eee WebKit`WebKit::NavigationState::NavigationClient::decidePolicyForNavigationResponse(WebKit::WebPageProxy&, WTF::Ref<API::NavigationResponse, WTF::DumbPtrTraits<API::NavigationResponse> >&&, WTF::Ref<WebKit::WebFramePolicyListenerProxy, WTF::DumbPtrTraits<WebKit::WebFramePolicyListenerProxy> >&&, API::Object*) + 404
    frame #7: 0x000000011acfb888 WebKit`WebKit::WebPageProxy::decidePolicyForResponse(unsigned long long, WebCore::SecurityOriginData const&, unsigned long long, WebCore::ResourceResponse const&, WebCore::ResourceRequest const&, bool, unsigned long long, WebKit::UserData const&) + 424
    frame #8: 0x000000011acfb9e8 WebKit`WebKit::WebPageProxy::decidePolicyForResponseSync(unsigned long long, WebCore::SecurityOriginData const&, unsigned long long, WebCore::ResourceResponse const&, WebCore::ResourceRequest const&, bool, unsigned long long, WebKit::UserData const&, bool&, WebCore::PolicyAction&, WebKit::DownloadID&) + 158
    frame #9: 0x000000011ad2b51f WebKit`void IPC::callMemberFunctionImpl<WebKit::WebPageProxy, void (WebKit::WebPageProxy::*)(unsigned long long, WebCore::SecurityOriginData const&, unsigned long long, WebCore::ResourceResponse const&, WebCore::ResourceRequest const&, bool, unsigned long long, WebKit::UserData const&, bool&, WebCore::PolicyAction&, WebKit::DownloadID&), std::__1::tuple<unsigned long long, WebCore::SecurityOriginData, unsigned long long, WebCore::ResourceResponse, WebCore::ResourceRequest, bool, unsigned long long, WebKit::UserData>, 0ul, 1ul, 2ul, 3ul, 4ul, 5ul, 6ul, 7ul, std::__1::tuple<bool, WebCore::PolicyAction, WebKit::DownloadID>, 0ul, 1ul, 2ul>(WebKit::WebPageProxy*, void (WebKit::WebPageProxy::*)(unsigned long long, WebCore::SecurityOriginData const&, unsigned long long, WebCore::ResourceResponse const&, WebCore::ResourceRequest const&, bool, unsigned long long, WebKit::UserData const&, bool&, WebCore::PolicyAction&, WebKit::DownloadID&), std::__1::tuple<unsigned long long, WebCore::SecurityOriginData, unsigned long long, WebCore::ResourceResponse, WebCore::ResourceRequest, bool, unsigned long long, WebKit::UserData>&&, std::__1::tuple<bool, WebCore::PolicyAction, WebKit::DownloadID>&, std::__1::integer_sequence<unsigned long, 0ul, 1ul, 2ul, 3ul, 4ul, 5ul, 6ul, 7ul>, std::__1::integer_sequence<unsigned long, 0ul, 1ul, 2ul>) + 100
    frame #10: 0x000000011ad20e6a WebKit`void IPC::handleMessage<Messages::WebPageProxy::DecidePolicyForResponseSync, WebKit::WebPageProxy, void (WebKit::WebPageProxy::*)(unsigned long long, WebCore::SecurityOriginData const&, unsigned long long, WebCore::ResourceResponse const&, WebCore::ResourceRequest const&, bool, unsigned long long, WebKit::UserData const&, bool&, WebCore::PolicyAction&, WebKit::DownloadID&)>(IPC::Decoder&, IPC::Encoder&, WebKit::WebPageProxy*, void (WebKit::WebPageProxy::*)(unsigned long long, WebCore::SecurityOriginData const&, unsigned long long, WebCore::ResourceResponse const&, WebCore::ResourceRequest const&, bool, unsigned long long, WebKit::UserData const&, bool&, WebCore::PolicyAction&, WebKit::DownloadID&)) + 261
    frame #11: 0x000000011ab41e2d WebKit`IPC::MessageReceiverMap::dispatchSyncMessage(IPC::Connection&, IPC::Decoder&, std::__1::unique_ptr<IPC::Encoder, std::__1::default_delete<IPC::Encoder> >&) + 141
    frame #12: 0x000000011ad77936 WebKit`WebKit::WebProcessProxy::didReceiveSyncMessage(IPC::Connection&, IPC::Decoder&, std::__1::unique_ptr<IPC::Encoder, std::__1::default_delete<IPC::Encoder> >&) + 28
    frame #13: 0x000000011ab0c6bb WebKit`IPC::Connection::dispatchSyncMessage(IPC::Decoder&) + 209
    frame #14: 0x000000011ab0a032 WebKit`IPC::Connection::dispatchMessage(std::__1::unique_ptr<IPC::Decoder, std::__1::default_delete<IPC::Decoder> >) + 104
    frame #15: 0x000000011ab0c8e3 WebKit`IPC::Connection::dispatchOneMessage() + 177
    frame #16: 0x000000012350e479 JavaScriptCore`WTF::RunLoop::performWork() + 329
    frame #17: 0x000000012350e6c2 JavaScriptCore`WTF::RunLoop::performWork(void*) + 34
    frame #18: 0x0000000116ac6bb1 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    frame #19: 0x0000000116aab4af CoreFoundation`__CFRunLoopDoSources0 + 271
    frame #20: 0x0000000116aaaa6f CoreFoundation`__CFRunLoopRun + 1263
    frame #21: 0x0000000116aaa30b CoreFoundation`CFRunLoopRunSpecific + 635
    frame #22: 0x000000011d7bfa73 GraphicsServices`GSEventRunModal + 62
    frame #23: 0x00000001148950b7 UIKit`UIApplicationMain + 159
    frame #24: 0x0000000107ad52b3 Chromium`(anonymous namespace)::RunUIApplicationMain(argc=1, argv=0x00007ffee812b1c0) at chrome_exe_main.mm:54
    frame #25: 0x0000000107ad4d83 Chromium`main(argc=1, argv=0x00007ffee812b1c0) at chrome_exe_main.mm:78
    frame #26: 0x000000011ebd6955 libdyld.dylib`start + 1

--Chrome Identity automated triaging--

This bug is Assigned and has gone one month without any activity, so it is being moved to Available to indicate that it is not actively being worked on. If you are working on this bug, please mark yourself as the owner and move back to Assigned. Please see https://goo.gl/78kbny for more details. Please remove the Services>SignIn or UI>Browser>Profiles components if this bug isn't related to Chrome Identity.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

--Chrome Identity automated triaging--

This bug is Assigned and has gone one month without any activity, so it is being moved to Available to indicate that it is not actively being worked on. If you are working on this bug, please mark yourself as the owner and move back to Assigned. Please see https://goo.gl/78kbny for more details. Please remove the Services>SignIn or UI>Browser>Profiles components if this bug isn't related to Chrome Identity.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

jlebel@: friendly triage ping. Any updates here?

Unfortunately I didn't have time yet to look into that bug.

I investigated a bit more on that bug. This doesn't seem to be a regression to me. We always had a short time while changing account without account (Chrome needs to update its token).
There is a race condition between the fact that gmail.com is reloaded while fetching the tokens.

The UI to change the sync account will disappear when we will ship Unity (issue 827072).

Also turning on Multilogin should help for this issue since Multilogin will fetch the tokens faster (issue 892130).

jlebel@: do you propose to close this as WontFix?