AppleScript: Tell Google Chrome to activate/deactivate extension
Try this code instead.

tell application "Google Chrome" to activate
tell application "System Events" to keystroke "u" using {option down, shift down}
delay(1)
tell application "System Events" to keystroke "r" using command down


I actually ran this applescript along with yours. First time I did not test yours seeing you called for a key code but gave it a keystroke value. When I ran your code, it gave me syntax errors(even with proper key code and keystroke values). When I ran my code, it compiles properly and runs the script as intended.