Move PathComponents from file_util to FilePath, add FilePath::IsParent()

base/file_util.h

Index: base/file_util.h
diff --git a/base/file_util.h b/base/file_util.h
index 39d8f093a170c09002a12730868ba4d5ff8c3d4c..30918d3d7d91e346d899c558512647012f9c1191 100644
--- a/base/file_util.h
+++ b/base/file_util.h
@@ -38,10 +38,6 @@ namespace file_util {
 //-----------------------------------------------------------------------------
 // Functions that operate purely on a path string w/o touching the filesystem:
 
-// Returns a vector of all of the components of the provided path.
-void PathComponents(const FilePath& path,
-                    std::vector<FilePath::StringType>* components);
-
 // Returns true if the given path ends with a path separator character.
 bool EndsWithSeparator(const FilePath& path);
 // These two versions are both deprecated. TODO(estade): remove them.