As China’s middle class grows, outbound tourism is expected to surge. Ctrip, China’s leading online travel agent, has ­already faced down stiff competition to become the dominant platform for China’s hundreds of millions of domestic tourists; it’s on target to see international travel deliver 40% to 50% of its revenue within a few years. Net revenue for the second quarter increased 13% year over year, to $1.1 billion. Ctrip’s biggest new challenge: doing battle with Chinese tech giants like Meituan and Tencent eager for a piece of the lucrative market.