None of these answers worked for me in a comprehensive way under Mac OS X Yosemite. Here is my solution, which gives you multiple instances, a dock launch menu for the instances, and different icons for each instance. When you run the script it'll automatically go through all your profiles, and then tell you what to do next.
#!/bin/bash
# cdi.sh - Make chrome profiles behave like multiple browsers on Mac OS X
# (Tested on Yoshmite). Make profiles work like seperate applications
# - esp. useful if you want to easily switch between different browsers
# in different virtual desktops / workspaces, or don't want work
# windows mixed in with home windows in the "Window" menu, or want to
# be able to easily see what processes are with a certain profile in
# chrome task manager, or be able to eaisly quit one profile with
# multiple windows open and start where you left of later.
set -e
cd /Users/$USER/Library/Application\ Support/Google/Chrome
CDI="cdi-chrome-multiple-profile-instances-in-dock-with-different-icons.d"
APPLESCRIPTS="$CDI/Applescript-Sources"
LAUNCHERS="$CDI/Chrome-Launchers"
RUNTIMES="$CDI/Chrome-Runtimes"
test -d $CDI || mkdir $CDI
test -d $APPLESCRIPTS || mkdir $APPLESCRIPTS
test -d $LAUNCHERS || mkdir $LAUNCHERS
test -d $RUNTIMES || mkdir $RUNTIMES
grep '"username"' Profile*/Preferences Default/Preferences | grep -v ' ' | awk -F : '{print $1";"$3}' | sed 's:/Preferences::g' | sed 's:\@:-at-:g' | sed 's/;\ /;/g' > $CDI/profiles.txt
# Like: Profile 1;"webmaster-at-example.org"
echo "Be patient, this involves copying a lot of data..."
while read PROFILE; do
DIR="$(echo $PROFILE | awk -F\; '{print $1}')"
# Like: DIR='Profile 1'
echo "Working on profile: $DIR"
LINK="$(echo $PROFILE | awk -F\; '{print $2}' | sed 's/\ /\-/g' | sed 's/"//g' | sed 's/^/cdi-profile-/g')"
# Like: cdi-profile-webmaster-at-example.org
APP="$(echo $LINK | sed 's/^cdi-profile-//g' | sed 's/$/-DO-NOT-RUN-DIRECTLY-JUST-USE-FOR-CHANGING-ICON-cdi\.app/g')"
# Like: webmaster-at-example.org-DO-NOT-RUN-DIRECTLY-JUST-USE-FOR-CHANGING-ICON-cdi.app
SHIM="$(echo $LINK | sed 's/^cdi-profile-//g' | sed 's/$/\.app/g')"
# Like: webmaster-at-example.org.app
TXT="$APPLESCRIPTS/$(echo $LINK | sed 's:^cdi-profile-:chrome-:g' | sed 's/$/\.txt/g')"
# Like:
# cdi-chrome-multiple-profile-instances-in-dock-with-different-icons.d
# /Applescript-Sources/chrome-webmaster-at-example.org.txt
test -L "$LINK" || ln -s "$DIR" "$LINK"
cd "$LINK"
test -L Default || ln -s . Default
cd /Users/$USER/Library/Application\ Support/Google/Chrome
test -d "$RUNTIMES/$APP" || cp -R /Applications/Google\ Chrome.app "$RUNTIMES/$APP"
## This section disabled because enabling it makes automatic profile login not work.
## There is a chance someone who knows more about chrome will help at some point; see:
## https://code.google.com/p/chromium/issues/detail?id=460787
## https://groups.google.com/a/chromium.org/forum/#!topic/chromium-discuss/0HEeMuh8WqA
## https://github.com/lhl/chrome-ssb-osx
# Change Bundle ID so desktop assignation works. Not sure if this will survive updates.
# CFBundleIdentifier must contain only alphanumeric (A-Z,a-z,0-9), hyphen (-), and period (.) characters.
# (Based on fiddling around there also seems to be a length limit.)
#UUID="$(echo $APP | md5sum | awk '{print $1}' | tr [0-9] [A-Z] | cut -c 1-4,29-32)"
#plutil -replace CFBundleIdentifier -string "cdi.$UUID" -- "$RUNTIMES/$APP/Contents/Info.plist"
#plutil -replace CFBundleName -string "$UUID" -- "$RUNTIMES/$APP/Contents/Info.plist"
#plutil -replace CFBundleDisplayName -string "$UUID" -- "$RUNTIMES/$APP/Contents/Info.plist"
#plutil -replace KSProductID -string "cdi.$UUID" -- "$RUNTIMES/$APP/Contents/Info.plist"
# To check: defaults read ~/Library/Preferences/com.apple.spaces.plist app-bindings
echo "on run" > $TXT
echo -n "do shell script " >> $TXT
echo -n '"' >> $TXT
echo -n "/Users/$USER/Library/Application\\\\ Support/Google/Chrome/$RUNTIMES/$APP/Contents/MacOS/Google\\\\ Chrome --user-data-dir=/Users/$USER/Library/Application\\\\ Support/Google/Chrome/$LINK" >> $TXT
echo ' > /dev/null 2>&1 &"' >> $TXT
echo "quit" >> $TXT
echo "end run" >> $TXT
test -d "$LAUNCHERS/$SHIM" || osacompile -o "$LAUNCHERS/$SHIM" $TXT
done < $CDI/profiles.txt
echo
echo 'Done with automated portion. Now you should manually:'
echo
echo '1. Add (identical) icons of your choice to each pair of profile Launchers'
echo ' / Runtimes in the folder ~/Library/Application Support/Google/Chrome/'
echo ' cdi-chrome-multiple-profile-instances-in-dock-with-different-icons.d'
echo ' (google for numerous guides on how to change mac os x app icons)'
echo
echo '2. From the finder, drag the "Chrome-Launchers" folder to the stacks area'
echo ' of the dock. Right click on the stack and select "List" for easy viewing.'
echo ' Also select "Display as Folder" and give the folder a nice icon.'
echo
echo '3. BE SURE to only open Chrome via this stack. DO NOT pin the app-area'
echo ' Chrome icon(s) to the app area of the dock! DO NOT run "normal" Chrome!'
echo
echo 'The only exception to (3) is if you need to add a new profile. In that case,'
echo 'close all instances, then open the "normal" Chrome, add profile, close, and'
echo 'then run this script again.'
echo
echo 'Note: when you launch first time you will get "Welcome to Google Chrome"'
echo ' dialog box. This is normal; do not worry. It will ask if you want'
echo ' to set Chrome as default; this applies to that instance of chrome.'
echo ' Choosy - http://www.choosyosx.com/ - works great with this!'
echo
For icons, you can use any PNG (or probably many other formats).
The chrome avatars which you may already be used to are located under "~/Library/Application Support/Google/Chrome/Avatars" - avatar_ninja.png etc.
Or make your own, or use one of the numerous icon sites - I like Easyicon.
Also this looks possibly useful - How to Get Back Avatars in Chrome to Switch User Profiles More Easily - to make the open windows easier to quickly identify (untested).
One thing that isn't working yet is the ability to assign different user profile chrome instances to specific desktops. This is because if the attribute used to do this is changed, the browser is no longer able to automatically log in to that profile when the browser starts up. I've made a forum post and bug report on this issue; it is also a problem for site-specific browsers, so the chrome-ssb-osx project may get this working at some point. I don't have the 10 reputation points needed to include more than 2 links in posts here (help! :-), so you'll have to look at the links to these things in the script above ("This section disabled" section).
Settings->Users
Chrome asks "Create a Desktop Shortcut for this User" and if you click yes it creates a shortcut that's the Chrome icon with the user's Chrome profile icon overlaid in the bottom right corner. When the app is running each profile has its own icon in the taskbar. I only bring this up because I'm hoping they eventually bring that feature to the macOS version.