Step 2 in porting disk cache to using FilePath.

net/disk_cache/entry_impl.cc

Index: net/disk_cache/entry_impl.cc
diff --git a/net/disk_cache/entry_impl.cc b/net/disk_cache/entry_impl.cc
index 163f217b3dc23bdc0a8c8d337565ba832a39db77..8749f260cecd0a0afe84e1892db8737b31da262b 100644
--- a/net/disk_cache/entry_impl.cc
+++ b/net/disk_cache/entry_impl.cc
@@ -692,7 +692,7 @@ File* EntryImpl::GetExternalFile(Addr address, int index) {
   if (!files_[index].get()) {
     // For a key file, use mixed mode IO.
     scoped_refptr<File> file(new File(kKeyFileIndex == index));
-    if (file->Init(backend_->GetFileName(address).ToWStringHack()))
+    if (file->Init(backend_->GetFileName(address)))
       files_[index].swap(file);
   }
   return files_[index].get();