ui: Cleanup class/struct forward declarations

ui/gl/gl_gl_api_implementation.h

 // 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.
 
 #ifndef UI_GL_GL_GL_API_IMPLEMENTATION_H_
 #define UI_GL_GL_GL_API_IMPLEMENTATION_H_
 
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_export.h"
 
 namespace base {
 class CommandLine;
 }
-namespace gpu {
-namespace gles2 {
-class GLES2Decoder;
-}
-}
+
 namespace gl {
 
 class GLContext;
-class GLSurface;
 struct GLVersionInfo;
 
 GL_EXPORT void InitializeStaticGLBindingsGL();
 void InitializeDynamicGLBindingsGL(GLContext* context);
 GL_EXPORT void InitializeDebugGLBindingsGL();
 void InitializeNullDrawGLBindingsGL();
 // TODO(danakj): Remove this when all test suites are using null-draw.
 bool HasInitializedNullDrawGLBindingsGL();
 bool SetNullDrawGLBindingsEnabledGL(bool enabled);
 GL_EXPORT void ClearGLBindingsGL();
@@ skipping 69 matching lines @@
 
   // Include the auto-generated part of this class. We split this because
   // it means we can easily edit the non-auto generated parts right here in
   // this file instead of having to edit some template or the code generator.
   #include "gl_bindings_api_autogen_gl.h"
 };
 
 }  // namespace gl
 
 #endif  // UI_GL_GL_GL_API_IMPLEMENTATION_H_