Allow POSIX callers to specify a new file's mode.

base/files/file_util.h

Index: base/files/file_util.h
diff --git a/base/files/file_util.h b/base/files/file_util.h
index ecc0d581dab8a29f70d6d1463c6aacd6d45b3e9a..c3aa3f1cf909cc220f24575f00754c13ddd056d2 100644
--- a/base/files/file_util.h
+++ b/base/files/file_util.h
@@ -322,6 +322,8 @@ BASE_EXPORT int ReadFile(const FilePath& filename, char* data, int max_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.
+// The file will be created with a default mode (POSIX) or security
+// descriptor (Windows). To specify a mode on POSIX, use |WriteFileWithMode|.
 BASE_EXPORT int WriteFile(const FilePath& filename, const char* data,
                           int size);
 
@@ -329,6 +331,12 @@ BASE_EXPORT int WriteFile(const FilePath& filename, const char* data,
 // Appends |data| to |fd|. Does not close |fd| when done.  Returns true iff
 // |size| bytes of |data| were written to |fd|.
 BASE_EXPORT bool WriteFileDescriptor(const int fd, const char* data, int size);
+
+// Writes the given buffer into the file, overwriting any data that was
+// previously there. Returns true iff |size| bytes of |data| were written to
+// |filename|. The file is created with the given |mode|.
+BASE_EXPORT bool WriteFileWithMode(const FilePath& filename, const char* data,
+                                   int size, mode_t mode);
 #endif
 
 // Appends |data| to |filename|.  Returns true iff |size| bytes of |data| were