ui: Add ref-counting to GLFence class.

ui/gl/gl_fence.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_FENCE_H_
 #define UI_GL_GL_FENCE_H_
 
 #include "base/macros.h"
+#include "base/memory/ref_counted.h"
 #include "ui/gl/gl_export.h"
 
 namespace gl {
 
-class GL_EXPORT GLFence {
+class GL_EXPORT GLFence : public base::RefCounted<GLFence> {
  public:
   GLFence();
-  virtual ~GLFence();
 
   static bool IsSupported();
-  static GLFence* Create();
+  static scoped_refptr<GLFence> Create();
 
   virtual bool HasCompleted() = 0;
   virtual void ClientWait() = 0;
 
   // Will block the server if supported, but might fall back to blocking the
   // client.
   virtual void ServerWait() = 0;
 
   // Returns true if re-setting state is supported.
   virtual bool ResetSupported();
 
   // Resets the fence to the original state.
   virtual void ResetState();
 
   // Loses the reference to the fence. Useful if the context is lost.
   virtual void Invalidate();
 
   // Returns true if signaling is supported.
   virtual bool SignalSupported();
 
   // Signal the fence.
   virtual void Signal();
 
+ protected:
+  virtual ~GLFence();
+
  private:
+  friend class base::RefCounted<GLFence>;
+
   DISALLOW_COPY_AND_ASSIGN(GLFence);
 };
 
 }  // namespace gl
 
 #endif  // UI_GL_GL_FENCE_H_