ui: Add ref-counting to GLFence class.

ui/gl/gl_fence_egl.h

 // 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.
 
 #ifndef UI_GL_GL_FENCE_EGL_H_
 #define UI_GL_GL_FENCE_EGL_H_
 
 #include "base/macros.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_export.h"
 #include "ui/gl/gl_fence.h"
 
 namespace gl {
 
 class GL_EXPORT GLFenceEGL : public GLFence {
  public:
   static void SetIgnoreFailures();
 
   GLFenceEGL();
-  ~GLFenceEGL() override;
 
   // GLFence implementation:
   bool HasCompleted() override;
   void ClientWait() override;
   void ServerWait() override;
 
  private:
+  ~GLFenceEGL() override;
+
   EGLSyncKHR sync_;
   EGLDisplay display_;
 
   DISALLOW_COPY_AND_ASSIGN(GLFenceEGL);
 };
 
 }  // namespace gl
 
 #endif  // UI_GL_GL_FENCE_EGL_H_