If you are assigned to Arm A or B, you will receive standard chemoradiation, erlotinib, and onartuzumab. You will be assigned to a dose level of onartuzumab based on when you join this study. After the first dose level of onartuzumab is given, you will be watched for 2 weeks after the end of radiation treatment to check for any serious side effects at that dose level. If any participants in this first group have intolerable side effects, a lower dose combination of the study drugs may be tested. Once the highest tolerable dose is found, extra participants will receive onartuzumab at that dose level.