Google is popular because it's good at what it does.
Graham specifically mentioned Google's Android Operating system for mobile phones and them bundling software into it at the competitive disadvantage to others such as Skype.
Skype is actually available as an app on the phone which can be downloaded from Google's own app store.
Android software is free for mobile phone manufacturers to use. The fact that it's free combined with how good the software is has led to its widespread adoption and success.
The software itself can be adapted by the manufacturers and some have removed Google search from Android, replacing it with competitor's search engines such as Microsoft's Bing. This obviously disadvantages Google significantly since the majority of their revenue is from adverts, many of which appear on Google searches. Hardly anti-competitive is it!
You can re-watch Graham's Westminster Hall debate at
Player it's at 16:00.