I too am having this same problem. I realize this is an old topic, but I have not found a solution. When I run chromium from terminal, I get nothing except the icon and Chromium in the taskbar. It's as though I have minimized the program, but I can't unminimize it. Right-clicking on chromium in the taskbar reveals the drop-down menu. Selecting close, closes the item on the taskbar and I then get the following in terminal:
code:[jim@jim-pc ~]$ chromium
[2095:2124:0622/052725.560305:ERROR:browser_gpu_channel_host_factory.cc(103)] Failed to launch GPU process.
^CNo valid task runner, exiting ungracefully.
Issue resolved: Today's update to chromium-59.0.3071.109-1 seems to have addressed the problem.