Thousands of McDonald’s workers seeking a minimum wage of $15 per hour swarmed the fast-food giant’s headquarters for the first of two days of protests to coincide with the fast-food chain’s annual meeting on Thursday. Protests by low-wage fast-food and retail workers have helped fuel a national debate about pay levels. Companies such as McDonald’s Corp (MCD.N) and Wal-Mart Stores Inc (WMT.N) are raising starting pay and cities like Seattle and Chicago are boosting their minimum wages over time.