ui: Add ref-counting to GLFence class.

ui/gl/gl_fence_shared_event.h

Index: ui/gl/gl_fence_shared_event.h
diff --git a/ui/gl/gl_fence_shared_event.h b/ui/gl/gl_fence_shared_event.h
index 23c185aa8cd3cfdc5f8d17672d41e1fcdaf479f8..caeab8471d0afa43a2580025f8a1d62380506a7d 100644
--- a/ui/gl/gl_fence_shared_event.h
+++ b/ui/gl/gl_fence_shared_event.h
@@ -15,7 +15,6 @@ namespace gl {
 class GL_EXPORT GLFenceSharedEvent : public GLFence {
  public:
   explicit GLFenceSharedEvent(const gfx::SharedEventHandle& handle);
-  ~GLFenceSharedEvent() override;
 
   // Overridden from GLFence:
   bool HasCompleted() override;
@@ -25,6 +24,8 @@ class GL_EXPORT GLFenceSharedEvent : public GLFence {
   void Signal() override;
 
  private:
+  ~GLFenceSharedEvent() override;
+
   gfx::SharedEvent shared_event_;
 
   DISALLOW_COPY_AND_ASSIGN(GLFenceSharedEvent);