Renderer process can allocate anonymous shared memory without help from browser process on Windows.

chrome/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 "chrome/renderer/print_web_view_helper.h"
 
 #include "base/file_descriptor_posix.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
@@ skipping 73 matching lines @@
 
   // Tell the browser we've finished writing the file.
   Send(new PrintHostMsg_TempFileForPrintingWritten(routing_id(),
                                                    sequence_number));
   return true;
 #else
   PrintHostMsg_DidPrintPage_Params printed_page_params;
   printed_page_params.data_size = 0;
   printed_page_params.document_cookie = params.params.document_cookie;
 
-  base::SharedMemoryHandle shared_mem_handle =
-      content::RenderThread::Get()->HostAllocateSharedMemoryBuffer(buf_size);
-  if (!base::SharedMemory::IsHandleValid(shared_mem_handle)) {
-    NOTREACHED() << "AllocateSharedMemoryBuffer returned bad handle";
-    return false;
-  }
+  {
+    scoped_ptr<base::SharedMemory> shared_mem(
+        content::RenderThread::Get()->HostAllocateSharedMemoryBuffer(
+            buf_size).release());
+    if (!shared_mem.get()) {
+      NOTREACHED() << "AllocateSharedMemoryBuffer failed";
+      return false;
+    }
 
-  {
-    base::SharedMemory shared_buf(shared_mem_handle, false);
-    if (!shared_buf.Map(buf_size)) {
+    if (!shared_mem->Map(buf_size)) {
       NOTREACHED() << "Map failed";
       return false;
     }
-    metafile.GetData(shared_buf.memory(), buf_size);
+    metafile.GetData(shared_mem->memory(), buf_size);
     printed_page_params.data_size = buf_size;
-    shared_buf.GiveToProcess(base::GetCurrentProcessHandle(),
-                             &(printed_page_params.metafile_data_handle));
+    shared_mem->GiveToProcess(base::GetCurrentProcessHandle(),
+                              &(printed_page_params.metafile_data_handle));
   }
 
   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;
   }
   return true;
 #endif  // defined(OS_CHROMEOS)
@@ skipping 86 matching lines @@
                          page_layout_in_points, *header_footer_info_,
                          params.params);
   }
   RenderPageContent(frame, params.page_number, canvas_area, content_area,
                     scale_factor, canvas.get());
 
   // Done printing. Close the device context to retrieve the compiled metafile.
   if (!metafile->FinishPage())
     NOTREACHED() << "metafile failed";
 }