4jyj is a malicious extension in Firefox and Chrome browser that hijacks the search engine, and redirects to yahoo.com when you search in Google. It also modifies your default search engine setting to something like DominantPartition. It cannot be removed by simply uninstalling any extension.
The following script shows how to find files
The string with numbers can be different on different systems.
cd ~/Library/Application\ Support/
sudo find . -name "*DominantPartition*"
sudo rm -rf ./.1047632777245170349/Services/com.DominantPartition.service ./.1047632777245170349/Services/com.DominantPartition.service/DominantPartition.service
cd ~/Library/LaunchAgents/
rm -rf com.DominantPartition.service.plist
cd /Library/Application\ Support/
sudo find . -name "*DominantPartition*"
sudo rm -rf ./.1047632777245170349/System/com.DominantPartition.system ./.1047632777245170349/System/com.DominantPartition.system/DominantPartition.system
cd /Library/LaunchDaemons/
sudo rm -rf com.DominantPartition*