Run Google Chrome with flags (not from chrome://flags)
You need to add the entire command into the /data/local/tmp/chrome-command-line file. For example, I usually you want to skip the "First run experience", and I do: 

# echo "chrome --disable-fre" &gt; /data/local/tmp/chrome-command-line

You probably need

# echo "chrome --sync-url whatever" &gt; /data/local/tmp/chrome-command-line