Relanding r71472....

Relanding r71472.

Use GL rather than EGL by default on linux. 

Debug Chromium builds display an error if they don't find EGL, even if GLX is available. This prompts people to install the EGL packages, even though that probably isn't their issue. 

Also, it looks like EGL, even if available, has some issues. 

If GLX isn't available, it still falls back to EGL. 

--use-gl=desktop should not be required to force use of GLX on boxes that also have EGL installed. 

Changed LOG(ERROR) to VLOG(1) if a shared library fails to load since this is not necessarily an error. Report an error only if no GL implementation can be initialized. Log which GL implementation was selected. 

TEST=launch chrome with various combinations of --use-gl switch and check the log output is correct. 
BUG=none