Add an AddExtension() method in FilePath

base/file_path.h

Index: base/file_path.h
diff --git a/base/file_path.h b/base/file_path.h
index 4d763eb394c1cca1eb11225a753a185f05e0c947..eb7279846a347413f858e9522cebd86a3f80b12c 100644
--- a/base/file_path.h
+++ b/base/file_path.h
@@ -242,13 +242,21 @@ class BASE_EXPORT FilePath {
   FilePath InsertBeforeExtensionASCII(
       const base::StringPiece& suffix) const WARN_UNUSED_RESULT;
 
+  // Adds |extension| to |file_name|. Returns the current FilePath if
+  // |extension| is empty. Returns "" if BaseName() == "." or "..".
+  FilePath AddExtension(

[Mark Mentovai, 2012/04/16 15:54:45]

It’s hard to see why you need to use this without a use case, but why is this
better than ReplaceExtension? Are you planning on having
a.filename.with.multiple.extensions?

[Devlin, 2012/04/17 21:52:49]

The most common instance I've encountered is when using a tempfile generated by
Chrome.  These files can take the form of org.Chromium.abc.xyz (real example:
/tmp/.org.chromium.Chromium.hAlw5V); when we use ReplaceExtension it results in
a different path, and the behavior of using ReplaceExtension can be different
than when passing in a non-temp file.  AddExtension makes it so that there's no
ambiguity.

+      const StringType& extension) const WARN_UNUSED_RESULT;
+
   // Replaces the extension of |file_name| with |extension|.  If |file_name|
-  // does not have an extension, them |extension| is added.  If |extension| is
+  // does not have an extension, then |extension| is added.  If |extension| is
   // empty, then the extension is removed from |file_name|.
   // Returns "" if BaseName() == "." or "..".
   FilePath ReplaceExtension(
       const StringType& extension) const WARN_UNUSED_RESULT;
 
+  // Returns true if BaseName() is "", ".", or "..".
+  bool IsBaseEmptyOrSpecialCase() const;

[Mark Mentovai, 2012/04/16 15:54:45]

Why do you need to expose this?

[Devlin, 2012/04/17 21:52:49]

My original thought was that these instances are fairly common occurrences of
paths people may wish to treat specially (or disallow).  However, I do not have
any concrete examples of when this would be the case; if you feel it better to
be moved to private scope (or within an anonymous namespace in the cc file
only), I'd be fine with that.

[Mark Mentovai, 2012/04/18 20:02:21]

D Cronin wrote:
I’d just hide this in the cc file.

[Devlin, 2012/04/19 00:05:42]

Done.

+
   // Returns true if the file path matches the specified extension. The test is
   // case insensitive. Don't forget the leading period if appropriate.
   bool MatchesExtension(const StringType& extension) const;