Just a year ago, Tencent Holdings Ltd. locked up one of the most coveted media franchises in the country when it paid $1.5 billion for five years of exclusive streaming rights to National Basketball Association games. A single tweet changed all that. Now, the Chinese social media giant may have to suspend airing those matchups — which drew half a billion viewers last year — after Houston Rockets General Manager Daryl Morey triggered a media blackout in China by tweeting support for Hong Kong’s pro-democracy protests. That sums up a disappointing 2019 for a company that looked like it was back on track after a horrendous 2018.