Google’s Android OS has more than 900 million users, the company said Wednesday as its I/O event began in San Francisco. Google also announced several APIs that will let developers add more capabilities to their Android apps, including in the areas of location and improving battery life. “It’s been an amazing year for Android developers,” said Android and Chrome vice president Sundar Pichai. Google has sent more money to developers through their Play Store sales in the last four months than it did in all of 2012 and revenue per user is now 2.5 times higher than it was a year ago, the company said.