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

ui/gl/gl_fence_arb.cc

 // Copyright 2014 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_fence_arb.h"
 
 #include "base/strings/stringprintf.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_context.h"
 
@@ skipping 60 matching lines @@
 
 void GLFenceARB::Invalidate() {
   sync_ = 0;
 }
 
 void GLFenceARB::HandleClientWaitFailure() {
   DCHECK(GLContext::GetCurrent());
   if (GLContext::GetCurrent()->WasAllocatedUsingRobustnessExtension()) {
     // This function pointer is only set if one of the robustness
     // extensions was available.
-    DCHECK(g_driver_gl.fn.glGetGraphicsResetStatusARBFn);
-    DCHECK(g_driver_gl.fn.glGetGraphicsResetStatusARBFn() != GL_NO_ERROR);
+    DCHECK(g_current_gl_driver &&
+           g_current_gl_driver->fn.glGetGraphicsResetStatusARBFn);
+    DCHECK(g_current_gl_driver->fn.glGetGraphicsResetStatusARBFn() !=
+           GL_NO_ERROR);
     LOG(ERROR) << "Failed to wait for GLFence; context was lost. Error code: "
                << GetGLErrors();
   } else {
     // There's no provision for reporting these failures higher up the
     // stack and thereby losing the context (or exiting the GPU
     // process) more cooperatively. Some of this code is called from
     // deep call stacks. Report the wait failure and crash with a log
     // message.
     LOG(FATAL) << "Failed to wait for GLFence. Error code: " << GetGLErrors();
   }
 }
 
 }  // namespace gl