Default to EGL instead of GLX with Ozone X11.

ui/ozone/platform/x11/x11_surface_factory.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/ozone/platform/x11/x11_surface_factory.h"
 
 #include <X11/Xlib.h>
 
 #include "third_party/khronos/EGL/egl.h"
 #include "ui/gfx/x/x11_types.h"
@@ skipping 141 matching lines @@
 X11SurfaceFactory::X11SurfaceFactory() {
   glx_implementation_.reset(new GLOzoneGLX());
   egl_implementation_.reset(new GLOzoneEGLX11());
 }
 
 X11SurfaceFactory::~X11SurfaceFactory() {}
 
 std::vector<gl::GLImplementation>
 X11SurfaceFactory::GetAllowedGLImplementations() {
   std::vector<gl::GLImplementation> impls;
+  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::kGLImplementationEGLGLES2);
   impls.push_back(gl::kGLImplementationOSMesaGL);
   return impls;
 }
 
 GLOzone* X11SurfaceFactory::GetGLOzone(gl::GLImplementation implementation) {
   switch (implementation) {
     case gl::kGLImplementationDesktopGL:
       return glx_implementation_.get();
     case gl::kGLImplementationEGLGLES2:
       return egl_implementation_.get();
     default:
       return nullptr;
   }
 }
 
 }  // namespace ui