Settling a second-hand smoke lawsuit brought by 60,000 flight attendants, the tobacco industry Friday agreed to pay $300 million to establish a research foundation on diseases blamed on cigarettes. The attendants had sued for $5 billion, claiming they developed lung, heart and other diseases by breathing other people’s smoke on airliners. The trial began four months ago. The settlement marks the first time the tobacco industry agreed to pay damages in a second-hand smoke lawsuit.