Patrick, would be useful to just do some sanity checks to see if we can repro this with other accounts.

FWIW I just tried with a clean profile on Windows (Chrome Canary) and repro'd this trivially. No sign (as yet) of it "recovering". 

Removing ChromeOS, since this seems specific to my Windows / Canary device.

Re-creating my ChromeOS profile, sync was very slow to start but did get into the working state after a bit.

Under Windows the browser shows "Sync First-Time Setup Complete" as false.

Could you include a screenshot of chrome://sync-internals from the canary device?

I haven't been able to reproduce this with new or existing accounts; one account was corp and two weren't. Tried on Windows, Linux and Mac, Canary and non-Canary.

When you say fresh profile, are you still using your @google.com credentials, just in the context of the new canary installation?

Yes, this is using my @google.com account, which has Sync data associated
with it, and signing in to Chrome, into a new local profile.

Confirmed that issue repros only if the user chooses the option to create a new profile, rather than "linking" their existing profile data to the signed-in account.

I was able to get a local repro. (FWIW I don't think is related to the mismatched birthday issue at all; the birthday error doesn't appear in the logs when reproducing. )

Instead I think this is a result of the following change: https://codereview.chromium.org/2442843002/

zmin@, I think your change prevents the sync settings for a "New Profile" corp account from ever being set. Can you confirm whether or not that's correct?

Bumping priority based on regression and confirmed repro. Looks like this regressed in 56.

Hi,

Yes, I bypass the sync confirm dialog in
https://codereview.chromium.org/2442843002/ because it's broken right now for the corp account. I have created an issue to track the problem:  crbug.com/657924 . Bypassing this dialog means the user never agree to sync his data so that the sync will be disabled by default.

As I mentioned in the ticket above, there're two issues in total. And the second one is the main reason I bypassed the dialog. Due to that issue, user only have a tiny time window to click the dialog(about 1~2 seconds, depends on how fast your computer) or the dialog will dismiss itself and end up with the same situation here.

Note that the second issue is now tracked separately:  crbug.com/663751 .

Is the issue corp-only, or does it affect all dasher accounts? Has the sync confirmation dialog always been broken in this scenario?

Yes, it will affect corp accounts which will see the dialog of "link data" and "create new profile". I'm not sure the dasher account, can you tell me what is it?

And yes, you can try to repo the issue by removing the bypass hack here:
https://cs.chromium.org/chromium/src/chrome/browser/ui/sync/one_click_signin_sync_starter.cc?q=one_click_signin_sync_starter.cc&sq=package:chromium&dr&l=485
Then sign in with any corp account and choose "Create a new profile".

This reproed with 1 of the 2 dasher accounts I used; it may depend on how sign in occurs(via the settings page or the chrome://chrome-signin page).

FWIW I used the Sign-in button from the user icon on the window title-bar.

So this is a duplicate of  Issue 657924 , which Owen already filed and assigned to Mihai. It sounds like the alternative right now is to have sync automatically start without the user getting a chance to really see the sync confirmation dialogue.

I agree that until we fix the underlying issues (navigating to the NTP in the new profile causes the sync confirmation dialogue to be dismissed quickly & that instead of canceling sync, this starts it immediately), we should just bypass the confirmation dialogue.

I'm marking as duplicate. We can follow up on the other bug.