Add the methods to change and get a posix file permission to file_util.

base/file_util.h

Index: base/file_util.h
diff --git a/base/file_util.h b/base/file_util.h
index 53eefcc4de1f2a71bb316a44bf97240dd70052dc..b148f96e45533384915a9490d1b6623c6fccd4fd 100644
--- a/base/file_util.h
+++ b/base/file_util.h
@@ -196,6 +196,14 @@ BASE_EXPORT bool CreateSymbolicLink(const FilePath& target,
 // Reads the given |symlink| and returns where it points to in |target|.
 // Returns false upon failure.
 BASE_EXPORT bool ReadSymbolicLink(const FilePath& symlink, FilePath* target);
+
+// Read the permission of the given |path|. |mode| is file permission bits.

[satorux1, 2012/07/03 06:16:55]

Read -> Reads

[satorux1, 2012/07/03 06:16:55]

Please also mention about how symbolic links are handled.

[yoshiki, 2012/07/04 07:57:57]

Done x2.

+BASE_EXPORT bool GetPosixFilePermissions(const FilePath& path,
+                                         mode_t* mode);

[satorux1, 2012/07/03 06:16:55]

Not sure if using mode_t is a good idea. we might want to define make it 'int'
and define easy-to-read enumerators like READ_BY_OTHERS than letting clients use
hard-to-read constants like  S_IROTH. 

[yoshiki, 2012/07/04 07:57:57]

Done.

+// Change the permission of the given |path|.

[satorux1, 2012/07/03 06:16:55]

Change -> Changes

[yoshiki, 2012/07/04 07:57:57]

Done.

+BASE_EXPORT bool ChangePosixFilePermissions(const FilePath& path,
+                                            mode_t mode_bits_to_set,
+                                            mode_t mode_bits_to_clear);

[satorux1, 2012/07/03 06:16:55]

I think taking two parameters for chaning the permissions is rather awkward.
Would be better to be compatible with chmod(2), that only takes one parameter.

[yoshiki, 2012/07/04 07:57:57]

Done. I added another method SetPosixFilePermissions().

 #endif  // defined(OS_POSIX)
 
 #if defined(OS_WIN)