Max to prioritize this feature request - I wonder also if setting the WelcomePageOnOSUpgradeEnabled=false policy might address this.

Update: I found a solution.

Use this:

  "first_run_tabs": [
    "http://www.example.com"
  ]

And set the URL to whatever your homepage is.  That effectively "fixes" it.

You can close this request.

I'm still really miffed about this, though.  You guys took away show_welcome_page and told NOBODY.  We just updated and -- lo and behold -- it no longer worked.  If you want enterprise to continue supporting you, then you're going to need to support enterprise. 

@Comment 2: As good as it is to have a workaround, it's not a solution, and so the request shouldn't be closed :)

Verified this issue in the latest version of Google Chrome Enterprise 58.0.3029.96

Just to update,
               Verified this issue on Skytap Env "Windows GPO Testing - Stable - K"
On disabling "WelcomePageOnOSUpgradeEnabled" policy, the "Welcome page"  is not displayed on the first run of chrome browser.

We have WelcomePageOnOSUpgradeEnabled disabled but still get the Welcome page in addition to the two startup pages.  We are not using a master_preferences, just GPO.  If I use try first_run_tabs inside master_preferences it gets more interesting.  So I set first_run_tabs in the master_preferences to "example.com" and if I have two startup pages in GPO "website1.com and website2.com" the following plays out:

1st run: No welcome page, just example.com
2nd run: Welcome page, website1.com, website2.com
3rd run: website1.com, website2.com

This is not good.  If I want a consistent experience I have to deploy master_preferences in addition to GPO startup pages?

Actually, if I deploy a master_preferences in tandem with GPO startup pages, then the 2nd run is the one with the welcome page.  Only the first and third+ run have the welcome page suppressed

Got the same Problem.

Welcome Page/Signin Page shown on Second run!

Google Chrome Enterprise 63.0.3239.132 x64

- Remove %Appdata%/Local/Google/Chrome Folder
- Start up Chrome, all Fine, Settings getting loaded from Profile File RoamingProfileSupportEnabled

- Second Startup the Damn Windows Popup, Looks like also 
  sync_promo.user_skipped also not honored in master_preferences

Unable to reproduce the issue on Windows machine, 

Steps Followed:
1. disabled WelcomePageOnOSUpgradeEnabled policy
2. launched the chrome for first time and observed a welcome page, Closed the browser.
3. Relaunch the chrome browser and observed no welcome page on 2nd run.

CC'ing the dev for further inputs

WelcomePageOnOSUpgradeEnabled is not meant to prevent the browser to show a welcome page on its first run but to prevent showing the new Win 10 welcome page after an OS Upgrade. 

If you want to control the first run behavior of the browser you need to use the https://www.chromium.org/administrators/policy-list-3#RestoreOnStartup and https://www.chromium.org/administrators/policy-list-3#RestoreOnStartupURLs policies.