[NaCl SDK} Add EventListener and EventEmitter to support epoll.

native_client_sdk/src/libraries/nacl_io/kernel_handle.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 LIBRARIES_NACL_IO_KERNEL_HANDLE_H_
 #define LIBRARIES_NACL_IO_KERNEL_HANDLE_H_
 
 #include <pthread.h>
 
 #include "nacl_io/error.h"
 #include "nacl_io/mount.h"
 #include "nacl_io/mount_node.h"
 #include "nacl_io/ostypes.h"
 
 #include "sdk_util/macros.h"
 #include "sdk_util/ref_object.h"
 #include "sdk_util/scoped_ref.h"
 #include "sdk_util/simple_lock.h"
 
 // KernelHandle provides a reference counted container for the open
 // file information, such as it's mount, node, access type and offset.
 // KernelHandle can only be referenced when the KernelProxy lock is held.
 class KernelHandle : public RefObject {
  public:
   KernelHandle();
   KernelHandle(const ScopedMount& mnt, const ScopedMountNode& node);
+  virtual ~KernelHandle();
 
   Error Init(int open_flags);
 
   // Assumes |out_offset| is non-NULL.
   Error Seek(off_t offset, int whence, off_t* out_offset);
 
   // Dispatches Read, Write, GetDents to atomically update offs_.
   Error Read(void* buf, size_t nbytes, int* bytes_read);
   Error Write(const void* buf, size_t nbytes, int* bytes_written);
   Error GetDents(struct dirent* pdir, size_t count, int* bytes_written);
 
   const ScopedRef<MountNode>& node();
   const ScopedRef<Mount>& mount();
 
 private:
   ScopedRef<MountNode> node_;
   ScopedRef<Mount> mount_;
   SimpleLock offs_lock_;
   size_t offs_;
 
   friend class KernelProxy;
   DISALLOW_COPY_AND_ASSIGN(KernelHandle);
 };
 
 typedef ScopedRef<KernelHandle> ScopedKernelHandle;
 
 #endif  // LIBRARIES_NACL_IO_KERNEL_HANDLE_H_