Documentation seems quite unambiguous:
* File name is master_preferences
* File location is the same as your chrome binary
https://www.chromium.org/administrators/configuring-other-preferences

Then this is a bug. 

-rwxr-xr-x 1 root root      1873 Apr 17 03:50 google-chrome
...
-rw-rw-r-- 1 root root       520 Apr 20 17:11 master_preferences
...

chrome@dev:/opt/google/chrome$ file google-chrome
google-chrome: Bourne-Again shell script, ASCII text executable

master_preferences file:

{
	"distribution": {
      		"chrome": true,
      		"do_not_launch_chrome" : true,
     		 "import_bookmarks": false,
      		"import_history": false,
      		"import_home_page": false,
      		"import_search_engine": false,
      		"make_chrome_default": false,
      		"make_chrome_default_for_user": false,
      		"require_eula": false,
      		"show_welcome_page": false,
		"skip_first_run_ui" : true, 
      		"suppress_first_run_default_browser_prompt": true,
      		"suppress_first_run_bubble": true
   }   
}

The user is still being prompted to set chrome as the default browser, and being asked in the same ui asking if they would like to send error reports.

Here is the screenshot:
https://imgur.com/a/fFTrOpH

I have also attached the screenshot.

Deleted: MakeGoogleDefault.PNG 949 KB

	MakeGoogleDefault.PNG 949 KB View Download

The only way I see to suppress that dialog is to set https://www.chromium.org/administrators/policy-list-3#MetricsReportingEnabled via enterprise policy.

As this is Enterprise related issue, hence routing it to Inhouse team for further inputs on this issue, adding TE-NeedsTriageFromHYD label and CCing: jmukthavaram@chromium.org.

Thanks!

yiningc@, Could you please take a look into this issue as we do not have Linux  debian Enterprise setup with us & removing 'TE-NeedsTriageFromHYD' label.

Thanks..!

Digging deeper, it looks like a master_preferences file of {"distribution":{"skip_first_run_ui":true}} used to suppress this dialog. This regressed back in Chrome 26 when skip_first_run_ui was removed.

Is the use of policies (https://www.chromium.org/administrators/linux-quick-start) an option for you?

Turns out this was previously reported for OS X, which also uses a first run dialog. Duping into the existing issue.

Hi. Please see https://bugs.chromium.org/p/chromium/issues/detail?id=224410#c27 for a policy-based way to suppress the first-run dialog.