A Cambodian online gambling ban is coming, which is expected to propel a new wave of Chinese investment in the nations casinos. The government said its gaming industry has been used by foreign criminals to extort money. The southern coastal city of Sihanoukville has emerged as a particular center for gambling and many of the dozens of Chinese-run casinos that have sprung up there have online gambling operations. China is Cambodia’s close ally, its biggest donor and investor . It has also been trying to crack down on cross-border gambling, criticizing operations in the Philippines that are similar to those…