Cleanup: Remove unneeded forward declarations in ppapi.

ppapi/cpp/file_system.h

 // Copyright (c) 2011 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 PPAPI_CPP_FILE_SYSTEM_H_
 #define PPAPI_CPP_FILE_SYSTEM_H_
 
 #include "ppapi/c/pp_file_info.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_stdint.h"
 #include "ppapi/c/pp_time.h"
 #include "ppapi/cpp/instance.h"
 #include "ppapi/cpp/resource.h"
 
 /// @file
 /// This file defines the API to create a file system associated with a file.
 
 struct PP_FileInfo;
 
 namespace pp {
 
 class CompletionCallback;
-class FileRef;
 
 /// The <code>FileSystem</code> class identifies the file system type
 /// associated with a file.
 class FileSystem : public Resource {
  public:
   /// Constructs an is_null() filesystem resource. If you use this constructor,
   /// you will have to assign it to a "real" FileSystem object before you can
   /// use it.
   FileSystem();
 
@@ skipping 12 matching lines @@
   /// @param[in] cc A <code>PP_CompletionCallback</code> to be called upon
   /// completion of Open().
   ///
   /// @return An int32_t containing an error code from <code>pp_errors.h</code>.
   int32_t Open(int64_t expected_size, const CompletionCallback& cc);
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_CPP_FILE_SYSTEM_H_