Give base::SharedMemory::CreateAnonymous an executable flag

content/public/common/child_process_sandbox_support_linux.h

 // 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 CONTENT_PULIC_COMMON_CHILD_PROCESS_SANDBOX_SUPPORT_LINUX_H_
 #define CONTENT_PULIC_COMMON_CHILD_PROCESS_SANDBOX_SUPPORT_LINUX_H_
 #pragma once
 
 #include <stdint.h>
 #include <string>
 
 #include "content/common/content_export.h"
 
 namespace content {
 
 // Returns a file descriptor for a shared memory segment.
-// The second argument is ignored because SHM segments are always
-// mappable with PROT_EXEC on Linux.
+// The executable flag indicates that we'll need to use mprotect
+// with PROT_EXEC after making a mapping, but not that we'll need
+// to mmap with PROT_EXEC in the first place.
 CONTENT_EXPORT int MakeSharedMemorySegmentViaIPC(size_t length,
                                                  bool executable);
 
 // Return a read-only file descriptor to the font which best matches the given
 // properties or -1 on failure.
 //   charset: specifies the language(s) that the font must cover. See
 // render_sandbox_host_linux.cc for more information.
 CONTENT_EXPORT int MatchFontWithFallback(const std::string& face, bool bold,
                                          bool italic, int charset);
 
 // GetFontTable loads a specified font table from an open SFNT file.
 //   fd: a file descriptor to the SFNT file. The position doesn't matter.
 //   table: the table in *big-endian* format, or 0 for the whole font file.
 //   output: a buffer of size output_length that gets the data.  can be 0, in
 //     which case output_length will be set to the required size in bytes.
 //   output_length: size of output, if it's not 0.
 //
 //   returns: true on success.
 CONTENT_EXPORT bool GetFontTable(int fd, uint32_t table, uint8_t* output,
                                  size_t* output_length);
 
 };  // namespace content
 
 #endif  // CONTENT_PULIC_COMMON_CHILD_PROCESS_SANDBOX_SUPPORT_LINUX_H_