A follow-up nit fix for jumplist file operations

base/files/file_util_win.cc

Index: base/files/file_util_win.cc
diff --git a/base/files/file_util_win.cc b/base/files/file_util_win.cc
index 629658447d848b53630c2638d4ae478990ba498b..81121f213693a3431f440c79b30f48c8a179d3cb 100644
--- a/base/files/file_util_win.cc
+++ b/base/files/file_util_win.cc
@@ -177,10 +177,7 @@ bool CopyDirectory(const FilePath& from_path, const FilePath& to_path,
   FilePath real_from_path = MakeAbsoluteFilePath(from_path);
   if (real_from_path.empty())
     return false;
-  // Note: it's important to use IsParent() here as string comparison would
-  // result in a false negative, e.g. on C:\bar\Foo versus C:\bar\FooOld.

[chengx, 2016/12/15 19:51:54]

grt@ 
nit: i think this comment is unnecessary. the FilePath API should be used
because it's the right thing. otherwise, why is this one use of IsParent so
important that this comment is justified in comparison to every other use of
IsParent in the codebase?

-  if (real_to_path.value().size() >= real_from_path.value().size() &&
-      real_from_path.IsParent(real_to_path)) {

[chengx, 2016/12/15 19:51:54]

grt@ 
this "optimization" seems wrong to me -- either a FilePath is treated like a
string (as was with the old code), or it's treated as a FilePath (as it is with
the call to IsParent). i think it's a mistake to mix the two like this.

+  if (real_to_path == real_from_path || real_from_path.IsParent(real_to_path)) {

[grt (UTC plus 2), 2016/12/15 21:28:32]

nit: no braces

     return false;
   }