Open the Windows Start menu and search for "Environment Variables".
Click on "Edit the system environment variables".
In the System Properties window, click on the "Environment Variables" button.
Under "User variables", click the "New" button.
Set "Variable name" to CHROME_EXECUTABLE and "Variable value" to the path of the Chrome executable file, e.g. C:\Program Files (x86)\Google\Chrome\Application\chrome.exe.