Google\'s $12.5bn purchase of US phone maker Motorola Mobility has been completed days after it received approval from the Chinese government. Chinese authorities said Google must keep its mobile software, Android, free for other device makers for up to five years. The acquisition is Google\'s biggest to date. It will enable Google to supercharge the Android ecosystem and will enhance competition in mobile computing. The internet search giant has also named a new management team for the phone handset maker. Motorola is a leading manufacturer of smartphones and other devices. Google\'s takeover of the business allows it to move into the manufacturing of phones and tablet computers for the first time.