Move content::MakeSharedMemorySegmentViaIPC into its own file

content/common/child_process_sandbox_support_impl_shm_linux.cc

+// 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.
+
+#include "base/pickle.h"
+#include "content/common/child_process_sandbox_support_impl_linux.h"
+#include "content/common/sandbox_methods_linux.h"
+#include "content/common/unix_domain_socket_posix.h"
+
+namespace content {
+
+int MakeSharedMemorySegmentViaIPC(size_t length, bool executable) {
+  Pickle request;
+  request.WriteInt(LinuxSandbox::METHOD_MAKE_SHARED_MEMORY_SEGMENT);
+  request.WriteUInt32(length);
+  request.WriteBool(executable);
+  uint8_t reply_buf[10];
+  int result_fd;
+  ssize_t result = UnixDomainSocket::SendRecvMsg(GetSandboxFD(),
+                                                 reply_buf, sizeof(reply_buf),
+                                                 &result_fd, request);
+  if (result == -1)
+    return -1;
+  return result_fd;
+}
+
+}  // namespace content