Don't allow path traversal paths on the base file helpers

base/file_util.cc

Index: base/file_util.cc
===================================================================
--- base/file_util.cc	(revision 175095)
+++ base/file_util.cc	(working copy)
@@ -152,6 +152,8 @@
 }
 
 bool ReadFileToString(const FilePath& path, std::string* contents) {
+  if (path.ReferencesParent())

[Nico, 2013/01/08 19:20:03]

Should this DCHECK(), so that devs trying to do this in a test don't waste 20
minutes trying to understand what's going on?

+    return false;
   FILE* file = OpenFile(path, "rb");
   if (!file) {
     return false;