Add external extensions json source in proper mac location.

base/file_util.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.
 
 // This file contains utility functions for dealing with the local
 // filesystem.
 
 #ifndef BASE_FILE_UTIL_H_
 #define BASE_FILE_UTIL_H_
 #pragma once
@@ skipping 641 matching lines @@
   FILE_SYSTEM_CGROUP,         // cgroup control.
   FILE_SYSTEM_OTHER,          // any other value.
   FILE_SYSTEM_TYPE_COUNT
 };
 
 // Attempts determine the FileSystemType for |path|.
 // Returns false if |path| doesn't exist.
 BASE_EXPORT bool GetFileSystemType(const FilePath& path, FileSystemType* type);
 #endif
 
+#if defined(OS_POSIX)
+// Test that |path| can only be changed by a specific user and group.
+// Specifically, test that all parts of |path| under (and including) |base|:
+// * Exist.
+// * Are owned by a specific user and group.

[Evan Martin, 2011/08/30 17:26:38]

Does it matter that you check the group, when you don't check whether it's
group-modifiable?

[Sam Kerner (Chrome), 2011/09/16 18:12:59]

I considered not checking group membership if the group can't write.  I chose
not to do this, because there is no legitimate reason any group other than admin
should own /Library/... paths on mac os, and admin can write to everything under
/Library/.  If some future user needs it we could add it, but loosening the test
makes it more complex, and it will not be exercised outside unit tests.

+// * Are not writable by all users.
+// * Are not symbolic links.
+// This is useful for checking that a config file is administrator-controlled.
+// |base| must contain |path|.
+BASE_EXPORT bool IsPathControlledByUser(const FilePath& base,
+                                        const FilePath& path,
+                                        uid_t owner_uid,
+                                        gid_t group_gid);
+
+// Is |path| writable only by a user with administrator privileges?
+// Check this by testing that |path|, and every parent directory including
+// the root of the filesystem, are owned by root, controlled by the group
+// "admin", are not writable by all users, and contain no symbolic links.

[Evan Martin, 2011/08/30 17:26:38]

What is "admin" here?  It is not true that my root directory is controlled by
that user.

[Sam Kerner (Chrome), 2011/09/16 18:12:59]

Updated to make it clear that this function is mac-specific.  Put it in #if
defined(OS_MACOSX).

+// Will return false if |path| does not exist.
+BASE_EXPORT bool IsPathControlledByAdmin(const FilePath& path);
+#endif  // defined(OS_POSIX)
+
 }  // namespace file_util
 
 // Deprecated functions have been moved to this separate header file,
 // which must be included last after all the above definitions.
 #include "base/file_util_deprecated.h"
 
 #endif  // BASE_FILE_UTIL_H_