make base::SharedMemoryHandle a class on POSIX.

components/printing/renderer/print_web_view_helper_linux.cc

 // 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.
 
 #include "components/printing/renderer/print_web_view_helper.h"
 
 #include <stddef.h>
 
 #include "base/logging.h"
 #include "build/build_config.h"
@@ skipping 76 matching lines @@
     return false;
   }
 
   printed_page_params.data_size = metafile.GetDataSize();
   printed_page_params.document_cookie = params.params.document_cookie;
 
   for (size_t i = 0; i < printed_pages.size(); ++i) {
     printed_page_params.page_number = printed_pages[i];
     Send(new PrintHostMsg_DidPrintPage(routing_id(), printed_page_params));
     // Send the rest of the pages with an invalid metafile handle.
-    printed_page_params.metafile_data_handle.fd = -1;
+    printed_page_params.metafile_data_handle.Release();
   }
   return true;
 #endif  // defined(OS_ANDROID)
 }
 #endif  // BUILDFLAG(ENABLE_BASIC_PRINTING)
 
 }  // namespace printing