AppleScript Get HTML of Chrome Active Tab
Here is one way to grab the HTML of the active tab of the front window of Google Chrome using AppleScript:

tell application "Google Chrome" to set sourceHTML to ¬
    execute front window's active tab javascript "document.documentElement.outerHTML"




Note: The example AppleScript code is just that and does not contain any error handling as may be appropriate. The onus is upon the user to add any error handling as may be appropriate, needed or wanted. Have a look at the try statement and error statement in the AppleScript Language Guide. See also, Working with Errors.