Namespace sandbox: add check for unprivileged use of CLONE_NEWUSER

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index 54b8cedddc6492e58b76379f8a87d50fe38185f7..ab674089a70857029a1bf9bf2511d5f486157dfe 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -11568,7 +11568,7 @@ Tell us what happened exactly before you got the profile error message:
         <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> can not be run as root.
       </message>
       <message name="IDS_REFUSE_TO_RUN_AS_ROOT_2" desc="Detailed message in the error dialog when the user tries to start Chrome as root.">
-        Please start <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> as a normal user. To run as root, you must specify an alternate --user-data-dir for storage of profile information.
+        Please start <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> as a normal user. If you need to run as root for development, rerun with the --no-sandbox flag.
       </message>
       <if expr="is_win">
         <message name="IDS_PROFILE_ON_NETWORK_WARNING" desc="Warning shown to the user when they are running Chrome on Windows with a profile located on a network share.">