Use LockFile/UnlockFile for Settings to port to Windows

util/misc/uuid.h

Index: util/misc/uuid.h
diff --git a/util/misc/uuid.h b/util/misc/uuid.h
index 29b36bc09b8c8c26ded6dd6e63effa7d23b5fb87..41bd0bef4079b9dfadb7111ea3bfcd7fbb5a1e16 100644
--- a/util/misc/uuid.h
+++ b/util/misc/uuid.h
@@ -84,6 +84,9 @@ struct UUID {
   base::string16 ToString16() const;
 #endif  // OS_WIN
 
+  //! \brief Uses a standard system facility to generate a new UUID.
+  static bool GenerateFromSystem(UUID* into);
+
   // These fields are laid out according to RFC 4122 §4.1.2.
   uint32_t data_1;
   uint16_t data_2;