Don't allow '\0' characters in FilePath.

base/file_path.h

 // 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.
 
 // FilePath is a container for pathnames stored in a platform's native string
 // type, providing containers for manipulation in according with the
 // platform's conventions for pathnames.  It supports the following path
 // types:
 //
 //                   POSIX            Windows
@@ skipping 35 matching lines @@
 // at all, making them safe to use without fear of blocking on I/O operations.
 // These methods do not function as mutators but instead return distinct
 // instances of FilePath objects, and are therefore safe to use on const
 // objects.  The objects themselves are safe to share between threads.
 //
 // To aid in initialization of FilePath objects from string literals, a
 // FILE_PATH_LITERAL macro is provided, which accounts for the difference
 // between char[]-based pathnames on POSIX systems and wchar_t[]-based
 // pathnames on Windows.
 //
+// Paths can't contain NULs as a precaution agaist premature truncation.
+//
 // Because a FilePath object should not be instantiated at the global scope,
 // instead, use a FilePath::CharType[] and initialize it with
 // FILE_PATH_LITERAL.  At runtime, a FilePath object can be created from the
 // character array.  Example:
 //
 // | const FilePath::CharType kLogFileName[] = FILE_PATH_LITERAL("log.txt");
 // |
 // | void Function() {
 // |   FilePath log_file_path(kLogFileName);
 // |   [...]
@@ skipping 270 matching lines @@
   // Returns a FilePath object from a path name in UTF-8. This function
   // should only be used for cases where you are sure that the input
   // string is UTF-8.
   //
   // Like AsUTF8Unsafe(), this function is unsafe. This function
   // internally calls SysWideToNativeMB() on POSIX systems other than Mac
   // and Chrome OS, to mitigate the encoding issue. See the comment at
   // AsUTF8Unsafe() for details.
   static FilePath FromUTF8Unsafe(const std::string& utf8);
 
-  void WriteToPickle(Pickle* pickle);
+  void WriteToPickle(Pickle* pickle) const;
   bool ReadFromPickle(PickleIterator* iter);
 
   // Normalize all path separators to backslash on Windows
   // (if FILE_PATH_USES_WIN_SEPARATORS is true), or do nothing on POSIX systems.
   FilePath NormalizePathSeparators() const;
 
   // Compare two strings in the same way the file system does.
   // Note that these always ignore case, even on file systems that are case-
   // sensitive. If case-sensitive comparison is ever needed, add corresponding
   // methods here.
@@ skipping 70 matching lines @@
 
 inline size_t hash_value(const FilePath& f) {
   return hash_value(f.value());
 }
 
 #endif  // COMPILER
 
 }  // namespace BASE_HASH_NAMESPACE
 
 #endif  // BASE_FILE_PATH_H_