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

ui/gl/init/gl_initializer_win.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/gl/init/gl_initializer.h"
 
 #include <dwmapi.h>
 
 #include "base/at_exit.h"
 #include "base/base_paths.h"
@@ skipping 232 matching lines @@
       }
       break;
     case kGLImplementationEGLGLES2:
       if (!GLSurfaceEGL::InitializeOneOff(GetDC(nullptr))) {
         LOG(ERROR) << "GLSurfaceEGL::InitializeOneOff failed.";
         return false;
       }
       break;
     case kGLImplementationOSMesaGL:
     case kGLImplementationMockGL:
+    case kGLImplementationStubGL:
       break;
     default:
       NOTREACHED();
   }
   return true;
 }
 
 bool InitializeStaticGLBindings(GLImplementation implementation) {
   // Prevent reinitialization with a different implementation. Once the gpu
   // unit tests have initialized with kGLImplementationMock, we don't want to
   // later switch to another GL implementation.
   DCHECK_EQ(kGLImplementationNone, GetGLImplementation());
 
   // Allow the main thread or another to initialize these bindings
   // after instituting restrictions on I/O. Going forward they will
   // likely be used in the browser process on most platforms. The
   // one-time initialization cost is small, between 2 and 5 ms.
   base::ThreadRestrictions::ScopedAllowIO allow_io;
 
   switch (implementation) {
     case kGLImplementationOSMesaGL:
       return InitializeStaticOSMesaInternal();
     case kGLImplementationEGLGLES2:
       return InitializeStaticEGLInternal();
     case kGLImplementationDesktopGL:
       return InitializeStaticWGLInternal();
     case kGLImplementationMockGL:
-      SetGLImplementation(kGLImplementationMockGL);
+    case kGLImplementationStubGL:
+      SetGLImplementation(implementation);
       InitializeStaticGLBindingsGL();
       return true;
     default:
       NOTREACHED();
   }
 
   return false;
 }
 
 void InitializeDebugGLBindings() {
   InitializeDebugGLBindingsEGL();
   InitializeDebugGLBindingsGL();
   InitializeDebugGLBindingsOSMESA();
   InitializeDebugGLBindingsWGL();
 }
 
 void ShutdownGLPlatform() {
   GLSurfaceEGL::ShutdownOneOff();
   ClearBindingsEGL();
   ClearBindingsGL();
   ClearBindingsOSMESA();
   ClearBindingsWGL();
 }
 
 }  // namespace init
 }  // namespace gl