Cleanup GrContextFactory and make it's subclasses private

include/gpu/gl/SkMesaGLContext.h

-
-/*
- * Copyright 2011 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-#ifndef SkMesaGLContext_DEFINED
-#define SkMesaGLContext_DEFINED
-
-#include "SkGLContext.h"
-
-#if SK_MESA
-
-class SkMesaGLContext : public SkGLContext {
-private:
-    typedef intptr_t Context;
-
-public:
-    virtual ~SkMesaGLContext() SK_OVERRIDE;
-    virtual void makeCurrent() const SK_OVERRIDE;
-    virtual void swapBuffers() const SK_OVERRIDE;
-
-    static SkMesaGLContext* Create(GrGLStandard forcedGpuAPI) {
-        if (kGLES_GrGLStandard == forcedGpuAPI) {
-            return NULL;
-        }
-        SkMesaGLContext* ctx = SkNEW(SkMesaGLContext);
-        if (!ctx->isValid()) {
-            SkDELETE(ctx);
-            return NULL;
-        }
-        return ctx;
-    }
-
-private:
-    SkMesaGLContext();
-    void destroyGLContext();
-
-    Context fContext;
-    GrGLubyte *fImage;
-};
-
-#endif
-
-#endif