Default to EGL instead of GLX with Ozone X11.

There is a bug destroying one of the XWindows created for the
VSyncProvider. When that bug is fixed the default should be GLX again.

BUG=646982

Review-Url: https://codereview.chromium.org/2339413002
Cr-Commit-Position: refs/heads/master@{#418879}

ui/ozone/platform/x11/x11_surface_factory.cc

@@ -159,8 +159,9 @@ X11SurfaceFactory::~X11SurfaceFactory() {}
 std::vector<gl::GLImplementation>
 X11SurfaceFactory::GetAllowedGLImplementations() {
   std::vector<gl::GLImplementation> impls;
-  impls.push_back(gl::kGLImplementationDesktopGL);
   impls.push_back(gl::kGLImplementationEGLGLES2);
+  // DesktopGL (GLX) should be the first option when crbug.com/646982 is fixed.
+  impls.push_back(gl::kGLImplementationDesktopGL);
   impls.push_back(gl::kGLImplementationOSMesaGL);
   return impls;
 }