SAN FRANCISCO — Canada and China need to keep in touch, Prime Minister Justin Trudeau said he told Xi Jinping during a chance encounter this week at the annual economic summit of Pacific Rim leaders that wrapped up Friday in northern California. Xi's four-hour meeting Wednesday with U.S. President Joe Biden was the highlight of an Asia-Pacific Economic Cooperation summit that was all about building an economic bulwark against China's growing influence. Trudeau's run-in was, by all accounts, purely perfunctory — they happened to be side-by-side during Thursday's traditional family photo — but he took a shot at some summit-sideline...