Reuse GLFenceNV when an existing CommandsCompletedQuery is reused

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 "ui/gl/gl_export.h"
 
 namespace gfx {
 
 class GL_EXPORT GLFence {
  public:
   GLFence();
   virtual ~GLFence();
 
   static bool IsSupported();
   static 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();
+
  private:
   DISALLOW_COPY_AND_ASSIGN(GLFence);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_FENCE_H_