Begin the first small step towards using FilePath everywhere:

base/file_util.h

 // Copyright (c) 2006-2008 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_
 
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #elif defined(OS_POSIX)
 #include <fts.h>
 #endif
 
 #include <stdio.h>
 
 #include <stack>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 
+class FilePath;
+
 namespace file_util {
 
 //-----------------------------------------------------------------------------
 // Constants
 
 extern const wchar_t kPathSeparator;
 
 
 //-----------------------------------------------------------------------------
 // Functions that operate purely on a path string w/o touching the filesystem:
@@ skipping 39 matching lines @@
 // path == "C:\pics\jojo.jpg",     returns "C:\pics"
 // path == "C:\Windows\system32\", returns "C:\Windows\system32"
 // path == "C:\Windows\system32",  returns "C:\Windows"
 std::wstring GetDirectoryFromPath(const std::wstring& path);
 
 // Appends new_ending to path, adding a separator between the two if necessary.
 void AppendToPath(std::wstring* path, const std::wstring& new_ending);
 
 // Convert provided relative path into an absolute path.  Returns false on
 // error.
+bool AbsolutePath(FilePath* path);
+// Deprecated temporary compatibility function.
 bool AbsolutePath(std::wstring* path);
 
 // Inserts |suffix| after the file name portion of |path| but before the
 // extension.
 // Examples:
 // path == "C:\pics\jojo.jpg" suffix == " (1)", returns "C:\pics\jojo (1).jpg"
 // path == "jojo.jpg"         suffix == " (1)", returns "jojo (1).jpg"
 // path == "C:\pics\jojo"     suffix == " (1)", returns "C:\pics\jojo (1)"
 // path == "C:\pics.old\jojo" suffix == " (1)", returns "C:\pics.old\jojo (1)"
 void InsertBeforeExtension(std::wstring* path, const std::wstring& suffix);
@@ skipping 24 matching lines @@
 #endif  // defined(OS_WIN)
 
 // Deletes the given path, whether it's a file or a directory.
 // If it's a directory, it's perfectly happy to delete all of the
 // directory's contents.  Passing true to recursive deletes
 // subdirectories and their contents as well.
 // Returns true if successful, false otherwise.
 //
 // WARNING: USING THIS WITH recursive==true IS EQUIVALENT
 //          TO "rm -rf", SO USE WITH CAUTION.
+bool Delete(const FilePath& path, bool recursive);
+// Deprecated temporary compatibility function.
 bool Delete(const std::wstring& path, bool recursive);
 
 // Moves the given path, whether it's a file or a directory.
 // Returns true if successful, false otherwise.
+bool Move(const FilePath& from_path, const FilePath& to_path);
+// Deprecated temporary compatibility function.
 bool Move(const std::wstring& from_path, const std::wstring& to_path);
 
 // Copies a single file. Use CopyDirectory to copy directories.
+bool CopyFile(const FilePath& from_path, const FilePath& to_path);
+// Deprecated temporary compatibility function.
 bool CopyFile(const std::wstring& from_path, const std::wstring& to_path);
 
 // Copies the given path, and optionally all subdirectories and their contents
 // as well.
 // If there are files existing under to_path, always overwrite.
 // Returns true if successful, false otherwise.
 // Dont't use wildcards on the names, it may stop working without notice.
 //
 // If you only need to copy a file use CopyFile, it's faster.
+bool CopyDirectory(const FilePath& from_path, const FilePath& to_path,
+                   bool recursive);
+// Deprecated temporary compatibility function.
 bool CopyDirectory(const std::wstring& from_path, const std::wstring& to_path,
                    bool recursive);
 
 // Returns true if the given path exists on the local filesystem,
 // false otherwise.
+bool PathExists(const FilePath& path);
+// Deprecated temporary compatibility function.
 bool PathExists(const std::wstring& path);
 
 // Returns true if the given path is writable by the user, false otherwise.
 bool PathIsWritable(const std::wstring& path);
 
 // Returns true if the given path exists and is a directory, false otherwise.
+bool DirectoryExists(const FilePath& path);
+// Deprecated temporary compatibility function.
 bool DirectoryExists(const std::wstring& path);
 
 #if defined(OS_WIN)
 // Gets the creation time of the given file (expressed in the local timezone),
 // and returns it via the creation_time parameter.  Returns true if successful,
 // false otherwise.
 bool GetFileCreationLocalTime(const std::wstring& filename,
                               LPSYSTEMTIME creation_time);
 
 // Same as above, but takes a previously-opened file handle instead of a name.
 bool GetFileCreationLocalTimeFromHandle(HANDLE file_handle,
                                         LPSYSTEMTIME creation_time);
 #endif  // defined(OS_WIN)
 
 // Returns true if the contents of the two files given are equal, false
 // otherwise.  If either file can't be read, returns false.
+bool ContentsEqual(const FilePath& filename1,
+                   const FilePath& filename2);
+// Deprecated temporary compatibility function.
 bool ContentsEqual(const std::wstring& filename1,
                    const std::wstring& filename2);
 
 // Read the file at |path| into |contents|, returning true on success.
 // Useful for unit tests.
 bool ReadFileToString(const std::wstring& path, std::string* contents);
 
 #if defined(OS_WIN)
 // Resolve Windows shortcut (.LNK file)
 // Argument path specifies a valid LNK file. On success, return true and put
@@ skipping 26 matching lines @@
                         const wchar_t *description, const wchar_t *icon,
                         int icon_index);
 
 // Return true if the given directory is empty
 bool IsDirectoryEmpty(const std::wstring& dir_path);
 
 #endif
 
   
 // Get the temporary directory provided by the system.
+bool GetTempDir(FilePath* path);
+// Deprecated temporary compatibility function.
 bool GetTempDir(std::wstring* path);
 
 // Creates a temporary file. The full path is placed in 'temp_file', and the
 // function returns true if was successful in creating the file. The file will
 // be empty and all handles closed after this function returns.
 // TODO(erikkay): rename this function and track down all of the callers.
 bool CreateTemporaryFileName(std::wstring* temp_file);
 
 // Same as CreateTemporaryFileName but the file is created in |dir|.
 bool CreateTemporaryFileNameInDir(const std::wstring& dir,
                                   std::wstring* temp_file);
 
 // Create a new directory under TempPath. If prefix is provided, the new
 // directory name is in the format of prefixyyyy.
 // If success, return true and output the full path of the directory created.
 bool CreateNewTempDirectory(const std::wstring& prefix,
                             std::wstring* new_temp_path);
 
 // Creates a directory, as well as creating any parent directories, if they
 // don't exist. Returns 'true' on successful creation, or if the directory
 // already exists.
+bool CreateDirectory(const FilePath& full_path);
+// Deprecated temporary compatibility function.
 bool CreateDirectory(const std::wstring& full_path);
 
 // Returns the file size. Returns true on success.
 bool GetFileSize(const std::wstring& file_path, int64* file_size);
 
 // Used to hold information about a given file path.  See GetFileInfo below.
 struct FileInfo {
   // The size of the file in bytes.  Undefined when is_directory is true.
   int64 size;
 
   // True if the file corresponds to a directory.
   bool is_directory;
 
   // Add additional fields here as needed.
 };
 
 // Returns information about the given file path.
 bool GetFileInfo(const std::wstring& file_path, FileInfo* info);
 
 // Wrapper for fopen-like calls. Returns non-NULL FILE* on success.
+FILE* OpenFile(const FilePath& filename, const char* mode);
+// Deprecated temporary compatibility functions.
 FILE* OpenFile(const std::string& filename, const char* mode);
 FILE* OpenFile(const std::wstring& filename, const char* mode);
 
 // Closes file opened by OpenFile. Returns true on success.
 bool CloseFile(FILE* file);
 
 // Reads the given number of bytes from the file into the buffer.  Returns
 // the number of read bytes, or -1 on error.
 int ReadFile(const std::wstring& filename, char* data, int size);
 
 // Writes the given buffer into the file, overwriting any data that was
 // previously there.  Returns the number of bytes written, or -1 on error.
 int WriteFile(const std::wstring& filename, const char* data, int size);
 
 // Gets the current working directory for the process.
+bool GetCurrentDirectory(FilePath* path);
+// Deprecated temporary compatibility function.
 bool GetCurrentDirectory(std::wstring* path);
 
 // Sets the current working directory for the process.
 bool SetCurrentDirectory(const std::wstring& current_directory);
 
 // A class for enumerating the files in a provided path. The order of the
 // results is not guaranteed.
 //
 // DO NOT USE FROM THE MAIN THREAD of your application unless it is a test
 // program where latency does not matter. This class is blocking.
@@ skipping 63 matching lines @@
 
 // Renames a file using the SHFileOperation API to ensure that the target file
 // gets the correct default security descriptor in the new path.
 bool RenameFileAndResetSecurityDescriptor(
     const std::wstring& source_file_path,
     const std::wstring& target_file_path);
 
 }  // namespace file_util
 
 #endif  // BASE_FILE_UTIL_H_