Convert resources to take an instance key instead of an Instance*.

ppapi/cpp/file_io.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 PPAPI_CPP_FILE_IO_H_
 #define PPAPI_CPP_FILE_IO_H_
 
 #include "ppapi/c/pp_time.h"
 #include "ppapi/cpp/resource.h"
 
 /// @file
 /// This file defines the API to create a file i/o object.
 
 struct PP_FileInfo;
 
 namespace pp {
 
 class CompletionCallback;
 class FileRef;
-class Instance;
+class InstanceHandle;
 
 /// The <code>FileIO</code> class represents a regular file.
 class FileIO : public Resource {
  public:
   /// Default constructor for creating an is_null() <code>FileIO</code>
   /// object.
   FileIO();
 
   /// A constructor used to create a <code>FileIO</code> and associate it with
   /// the provided <code>Instance</code>.
   ///
-  /// @param[in] instance An <code>Instance</code>.
-  FileIO(Instance* instance);
+  /// @param[in] instance The instance with which this resource will be
+  /// associated.
+  explicit FileIO(const InstanceHandle& instance);
 
   /// The copy constructor for <code>FileIO</code>.
   ///
   /// @param[in] other A pointer to a <code>FileIO</code>.
   FileIO(const FileIO& other);
 
   /// Open() opens the specified regular file for I/O according to the given
   /// open flags, which is a bit-mask of the PP_FileOpenFlags values.  Upon
   /// success, the corresponding file is classified as "in use" by this FileIO
   /// object until such time as the FileIO object is closed or destroyed.
@@ skipping 106 matching lines @@
   ///
   /// <strong>Note:</strong> If the FileIO object is destroyed, and it is still
   /// open, then it will be implicitly closed, so you are not required to call
   /// Close().
   void Close();
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_CPP_FILE_IO_H_