ui: Add ref-counting to GLFence class.

ui/gl/gl_fence_libsync.h

Index: ui/gl/gl_fence_libsync.h
diff --git a/ui/gl/gl_fence_libsync.h b/ui/gl/gl_fence_libsync.h
index bd24c1e7afd2b3602d4187e2a2ec38ed1d977874..7da1d4d2d67897b33d2f2a1ae7aacc7e2f1602dc 100644
--- a/ui/gl/gl_fence_libsync.h
+++ b/ui/gl/gl_fence_libsync.h
@@ -16,7 +16,6 @@ namespace gl {
 class GL_EXPORT GLFenceLibsync : public GLFence {
  public:
   explicit GLFenceLibsync(base::ScopedFD fd);
-  ~GLFenceLibsync() override;
 
   // Overridden from GLFence:
   bool HasCompleted() override;
@@ -24,6 +23,8 @@ class GL_EXPORT GLFenceLibsync : public GLFence {
   void ServerWait() override;
 
  private:
+  ~GLFenceLibsync() override;
+
   base::ScopedFD fd_;
 
   DISALLOW_COPY_AND_ASSIGN(GLFenceLibsync);