[NaCl SDK] nacl_io: big refactor to return error value (errno).

native_client_sdk/src/libraries/nacl_io/mount_passthrough.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_MOUNT_PASSTHROUGH_H_
 #define LIBRARIES_NACL_IO_MOUNT_PASSTHROUGH_H_
 
 #include "nacl_io/mount.h"
 
 class MountPassthrough : public Mount {
  protected:
   MountPassthrough();
 
-  virtual bool Init(int dev, StringMap_t& args, PepperInterface* ppapi);
+  virtual Error Init(int dev, StringMap_t& args, PepperInterface* ppapi);
   virtual void Destroy();
 
  public:
-  virtual MountNode *Open(const Path& path, int mode);
-  virtual MountNode *OpenResource(const Path& path);
-  virtual int Unlink(const Path& path);
-  virtual int Mkdir(const Path& path, int perm);
-  virtual int Rmdir(const Path& path);
-  virtual int Remove(const Path& path);
+  virtual Error Open(const Path& path, int mode, MountNode** out_node);
+  virtual Error OpenResource(const Path& path, MountNode** out_node);
+  virtual Error Unlink(const Path& path);
+  virtual Error Mkdir(const Path& path, int perm);
+  virtual Error Rmdir(const Path& path);
+  virtual Error Remove(const Path& path);
 
 private:
   friend class Mount;
   DISALLOW_COPY_AND_ASSIGN(MountPassthrough);
 };
 
 #endif  // LIBRARIES_NACL_IO_MOUNT_PASSTHROUGH_H_