try to use flags in Chrome command line without ROOT I use guide Run Chromium with flags My phone is not ROOTed.
With agreement of that guide with flags its can be done. May be, anyone try it? 
at that guide was said:For production build on a non-rooted device, you need to enable "Enable command line on non-rooted devices" in about:flags, then set command line in /data/local/tmp/chrome-command-line, finally manually restart ...

Chrome version 74.0.3729.136

I successfully set up flag "Enable command line on non-rooted devices". But then I need to copy data file to "/data/local/tmp/chrome-command-line" - and I ca not do that!

I tryed:


Command like that: 
C*:\WINDOWS\system32>adb shell 'echo --unsafely-treat-insecure-origin-as-secure=TestTest > /data/local/tmp/chrome-command-line'*
The system cannot find the path specified.
recomendation from that question, 
 # echo "chrome --sync-url whatever" > /data/local/tmp/chrome-command-line
use different android OS (5-7).
use construction like that  for copy files:
run-as com.example.app "cat /sdcard/temp_prefs.xml > shared_prefs/com.example.app_preferences.xml"


but nothing happend.
Its worked. You need set flag and next:
Command line like that: 

adb shell

shell@:/ $ echo "chrome --user-agent=MyUser" > /data/local/tmp/chrome-command-line

For check, you can download file from phone


  adb pull /data/local/tmp/iron-command-line d:\