Cleanup GrContextFactory and make it's subclasses private

include/gpu/gl/SkDebugGLContext.h

-
-/*
- * Copyright 2012 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-#ifndef SkDebugGLContext_DEFINED
-#define SkDebugGLContext_DEFINED
-
-#include "SkGLContext.h"
-
-class SkDebugGLContext : public SkGLContext {
-public:
-    virtual ~SkDebugGLContext() SK_OVERRIDE;
-    virtual void makeCurrent() const SK_OVERRIDE {}
-    virtual void swapBuffers() const SK_OVERRIDE {}
-
-    static SkDebugGLContext* Create(GrGLStandard forcedGpuAPI) {
-        if (kGLES_GrGLStandard == forcedGpuAPI) {
-            return NULL;
-        }
-        return SkNEW(SkDebugGLContext);
-    }
-private:
-    SkDebugGLContext();
-};
-
-#endif