LOS ANGELES/SAN FRANCISCO (Reuters) – Chipotle Mexican Grill Inc executives on Wednesday said they are confident that steps they are taking to tighten food safety at the popular burrito chain will prevent future food poisoning outbreaks. The company, which has won over diners and forced change on the restaurant industry by serving fresher, less-processed food, is grappling to overcome a series of outbreaks that have driven away diners, hammered its high-flying stock and spawned both a federal criminal probe and a shareholder lawsuit.