Use OSMesa when running Sky tests
Use OSMesa when running Sky tests

This CL switches us to use OSMesa rather than the system GL implementation when
running the Sky tests. This makes the tests more machine-independent and also
makes them work properly in Chromoting and in VirtualBox.

R=ojan@chromium.org, esprehn@chromium.org

Review URL: https://codereview.chromium.org/680243002

xunmengfeng/engine,axinging/sky_engine,tvolkert/engine,mpcomplete/flutter_engine,TribeMedia/sky_engine,tvolkert/engine,takaaptech/sky_engine,axinging/sky_engine,mxia/engine,mikejurka/engine,afandria/sky_engine,krisgiesing/sky_engine,flutter/engine,aam/engine,mdakin/engine,lyceel/engine,axinging/sky_engine,chinmaygarde/flutter_engine,mpcomplete/engine,Hixie/sky_engine,Hixie/sky_engine,jason-simmons/sky_engine,aam/engine,jamesr/sky_engine,lyceel/engine,chinmaygarde/sky_engine,lyceel/engine,mpcomplete/engine,iansf/sky_engine,jamesr/flutter_engine,zhangxq5012/sky_engine,qiankunshe/sky_engine,abarth/sky_engine,iansf/sky_engine,jason-simmons/sky_engine,abarth/sky_engine,axinging/sky_engine,jimsimon/sky_engine,chinmaygarde/flutter_engine,cdotstout/sky_engine,xunmengfeng/engine,chinmaygarde/flutter_engine,krisgiesing/sky_engine,zhangxq5012/sky_engine,zhangxq5012/sky_engine,mpcomplete/engine,qiankunshe/sky_engine,xunmengfeng/engine,cdotstout/sky_engine,flutter/engine,jamesr/flutter_engine,flutter/engine,devoncarew/sky_engine,aam/engine,zhangxq5012/sky_engine,TribeMedia/sky_engine,tvolkert/engine,TribeMedia/sky_engine,jimsimon/sky_engine,mpcomplete/flutter_engine,takaaptech/sky_engine,flutter/engine,mdakin/engine,Hixie/sky_engine,iansf/sky_engine,Hixie/sky_engine,devoncarew/sky_engine,mdakin/engine,lyceel/engine,flutter/engine,afandria/sky_engine,mxia/engine,xunmengfeng/engine,mpcomplete/flutter_engine,devoncarew/engine,takaaptech/sky_engine,jamesr/sky_engine,aam/engine,mxia/engine,jason-simmons/flutter_engine,mpcomplete/engine,jamesr/sky_engine,jamesr/sky_engine,afandria/sky_engine,mdakin/engine,jamesr/flutter_engine,TribeMedia/sky_engine,jason-simmons/flutter_engine,Hixie/sky_engine,tvolkert/engine,flutter/engine,afandria/sky_engine,abarth/sky_engine,jamesr/sky_engine,mikejurka/engine,takaaptech/sky_engine,takaaptech/sky_engine,jimsimon/sky_engine,Hixie/sky_engine,chinmaygarde/sky_engine,Hixie/sky_engine,aam/engine,chinmaygarde/sky_engine,jason-simmons/flutter_engine,devoncarew/engine,mikejurka/engine,krisgiesing/sky_engine,afandria/sky_engine,jamesr/sky_engine,takaaptech/sky_engine,chinmaygarde/sky_engine,aam/engine,jason-simmons/flutter_engine,aam/engine,rmacnak-google/engine,qiankunshe/sky_engine,TribeMedia/sky_engine,rmacnak-google/engine,qiankunshe/sky_engine,devoncarew/sky_engine,xunmengfeng/engine,afandria/sky_engine,jason-simmons/flutter_engine,iansf/sky_engine,cdotstout/sky_engine,mikejurka/engine,iansf/sky_engine,mdakin/engine,tvolkert/engine,afandria/sky_engine,jason-simmons/sky_engine,takaaptech/sky_engine,chinmaygarde/flutter_engine,takaaptech/sky_engine,mdakin/engine,mxia/engine,iansf/sky_engine,jason-simmons/sky_engine,zhangxq5012/sky_engine,chinmaygarde/sky_engine,mikejurka/engine,mpcomplete/engine,lyceel/engine,rmacnak-google/engine,rmacnak-google/engine,axinging/sky_engine,cdotstout/sky_engine,jamesr/flutter_engine,mpcomplete/flutter_engine,qiankunshe/sky_engine,mikejurka/engine,xunmengfeng/engine,TribeMedia/sky_engine,jason-simmons/flutter_engine,zhangxq5012/sky_engine,jamesr/flutter_engine,jamesr/flutter_engine,jimsimon/sky_engine,abarth/sky_engine,devoncarew/engine,mdakin/engine,jason-simmons/flutter_engine,mpcomplete/engine,mikejurka/engine,devoncarew/engine,chinmaygarde/flutter_engine,zhangxq5012/sky_engine,jimsimon/sky_engine,chinmaygarde/flutter_engine,krisgiesing/sky_engine,axinging/sky_engine,aam/engine,devoncarew/engine,rmacnak-google/engine,devoncarew/engine,cdotstout/sky_engine,jimsimon/sky_engine,zhangxq5012/sky_engine,axinging/sky_engine,devoncarew/sky_engine,cdotstout/sky_engine,abarth/sky_engine,flutter/engine,jimsimon/sky_engine,axinging/sky_engine,mpcomplete/flutter_engine,takaaptech/sky_engine,devoncarew/engine,Hixie/sky_engine,xunmengfeng/engine,jamesr/flutter_engine,mpcomplete/engine,axinging/sky_engine,devoncarew/sky_engine,jimsimon/sky_engine,abarth/sky_engine,tvolkert/engine,lyceel/engine,mxia/engine,krisgiesing/sky_engine,chinmaygarde/sky_engine,mxia/engine,abarth/sky_engine,jamesr/sky_engine,jason-simmons/sky_engine,afandria/sky_engine,mpcomplete/flutter_engine,jason-simmons/sky_engine,krisgiesing/sky_engine,jason-simmons/sky_engine,mpcomplete/engine,devoncarew/sky_engine,qiankunshe/sky_engine,jamesr/flutter_engine,mxia/engine,lyceel/engine,chinmaygarde/sky_engine,rmacnak-google/engine,jamesr/flutter_engine,mdakin/engine,qiankunshe/sky_engine,qiankunshe/sky_engine,mxia/engine,mikejurka/engine,krisgiesing/sky_engine,jimsimon/sky_engine,TribeMedia/sky_engine,chinmaygarde/flutter_engine,flutter/engine,tvolkert/engine,cdotstout/sky_engine,rmacnak-google/engine,mikejurka/engine,jason-simmons/flutter_engine,iansf/sky_engine,zhangxq5012/sky_engine,devoncarew/sky_engine,TribeMedia/sky_engine,iansf/sky_engine,TribeMedia/sky_engine