Implement the filesystem proxy. This allows the FileRef tests to pass in the...

ppapi/c/dev/ppb_file_system_dev.h

-/* Copyright (c) 2010 The Chromium Authors. All rights reserved.
+/* 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_C_DEV_PPB_FILE_SYSTEM_DEV_H_
 #define PPAPI_C_DEV_PPB_FILE_SYSTEM_DEV_H_
 
 #include "ppapi/c/dev/pp_file_info_dev.h"
+#include "ppapi/c/pp_bool.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/c/pp_stdint.h"
 #include "ppapi/c/pp_time.h"
 
 struct PP_CompletionCallback;
 
-#define PPB_FILESYSTEM_DEV_INTERFACE "PPB_FileSystem(Dev);0.3"
+#define PPB_FILESYSTEM_DEV_INTERFACE "PPB_FileSystem(Dev);0.4"
 
 struct PPB_FileSystem_Dev {
-  // Creates a weak pointer to the filesystem of the given type.
+  /** Creates a filesystem object of the given type. */
   PP_Resource (*Create)(PP_Instance instance, PP_FileSystemType_Dev type);
 
-  // Opens the file system. A file system must be opened before running any
-  // other operation on it.
+  /** Returns PP_TRUE if the given resource is a FileSystem. */
+  PP_Bool (*IsFileSystem)(PP_Resource resource);
+
+  /**
+   * Opens the file system. A file system must be opened before running any
+   * other operation on it.
+   *
+   * TODO(brettw) clarify whether this must have completed before a file can
+   * be opened in it.
+   */
   int32_t (*Open)(PP_Resource file_system,
                   int64_t expected_size,
                   struct PP_CompletionCallback callback);
+
+  /**
+   * Returns the type of the given file system.
+   *
+   * Returns PP_FILESYSTEMTYPE_NONE if the given resource is not a valid
+   * filesystem. It is valid to call this function even before Open completes.
+   */
+  PP_FileSystemType_Dev (*GetType)(PP_Resource file_system);
 };
 
 #endif  /* PPAPI_C_DEV_PPB_FILE_SYSTEM_DEV_H_ */