Refactor GL bindings so there is no global GLApi or DriverGL.

ui/gl/gl_context_osmesa.cc

 // Copyright (c) 2012 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/gl/gl_context_osmesa.h"
 
 #include <GL/osmesa.h>
 
 #include "base/logging.h"
 #include "ui/gfx/geometry/size.h"
@@ skipping 64 matching lines @@
                          size.width(),
                          size.height())) {
     LOG(ERROR) << "OSMesaMakeCurrent failed.";
     Destroy();
     return false;
   }
   // Track that we're no longer in a released state to workaround a mesa issue.
   is_released_ = false;
 
   // Set this as soon as the context is current, since we might call into GL.
-  SetRealGLApi();
+  BindGLApi();
 
   // Row 0 is at the top.
   OSMesaPixelStore(OSMESA_Y_UP, 0);
 
   SetCurrent(surface);
   InitializeDynamicBindings();
 
   if (!surface->OnMakeCurrent(this)) {
     LOG(ERROR) << "Could not make current.";
     return false;
@@ skipping 51 matching lines @@
 
 void GLContextOSMesa::OnSetSwapInterval(int interval) {
   DCHECK(IsCurrent(nullptr));
 }
 
 GLContextOSMesa::~GLContextOSMesa() {
   Destroy();
 }
 
 }  // namespace gl