[NaCl SDK] Expose Google Drive to nacl_io.

native_client_sdk/src/libraries/nacl_io/googledrivefs/googledrivefs.h

+// Copyright 2016 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.
+
+#include "nacl_io/filesystem.h"
+#include "nacl_io/typed_fs_factory.h"
+
+namespace nacl_io {
+
+class GoogleDriveFs : public Filesystem {
+ protected:
+  GoogleDriveFs();
+
+  Error Init(const FsInitArgs& args);
+
+ public:
+  Error OpenWithMode(const Path& path,
+                     int open_flags,
+                     mode_t mode,
+                     ScopedNode* out_node);
+  Error Unlink(const Path& path);
+  Error Mkdir(const Path& path, int permissions);
+  Error Rmdir(const Path& path);
+  Error Remove(const Path& path);
+  Error Rename(const Path& path, const Path& newPath);
+
+  std::string token();
+
+ private:
+  Error IsEmptyDir(const std::string& dir_id, bool* out_is_empty_dir);
+
+  std::string token_;
+
+  friend class TypedFsFactory<GoogleDriveFs>;
+};
+
+}  // namespace nacl_io