How to change the size of a Google Hangouts window in AppleScript?
This works for me with my actual Gmail information inserted at the two appropriate places in the script



tell application "Default knipolnnllmklapflnccelgolnpehhpl"
    activate
end tell
tell application "System Events"
    set theSBounds to {{405, 23}, {1037, 633}}
    set position of window "Google Hangouts - username@gmail.com" of application process "Google Chrome" to item 1 of theSBounds --replace username@gmail.com with your actual Gmail information
    set size of window "Google Hangouts - username@gmail.com" of application process "Google Chrome" to item 2 of theSBounds  --replace username@gmail.com with your actual Gmail information
end tell