Add FilePath::FinalExtension and RemoveFinalExtension

base/files/file_path.cc

Index: base/files/file_path.cc
diff --git a/base/files/file_path.cc b/base/files/file_path.cc
index 90cf40f4da8453396bae2e473c9865aaa3f27ab2..f8fb8b479469e39d64d9a32795a59f9e77297b15 100644
--- a/base/files/file_path.cc
+++ b/base/files/file_path.cc
@@ -18,6 +18,8 @@ const FilePath::CharType FilePath::kSeparators[] = FILE_PATH_LITERAL("/");
 #endif  // FILE_PATH_USES_WIN_SEPARATORS
 
 const FilePath::CharType FilePath::kCurrentDirectory[] = FILE_PATH_LITERAL(".");
+const FilePath::CharType FilePath::kParentDirectory[] = FILE_PATH_LITERAL("..");
+const FilePath::CharType FilePath::kExtensionSeparator = FILE_PATH_LITERAL('.');
 
 typedef FilePath::StringType StringType;
 
@@ -190,6 +192,25 @@ FilePath FilePath::BaseName() const {
   return new_path;
 }
 
+StringType FilePath::FinalExtension() const {
+  StringType base(BaseName().value());
+  // Special case "." and ".."
+  if (base == FilePath::kCurrentDirectory || base == FilePath::kParentDirectory)
+    return StringType();
+  const StringType::size_type dot = base.rfind(FilePath::kExtensionSeparator);
+  if (dot == StringType::npos)
+    return StringType();
+
+  return base.substr(dot, StringType::npos);
+}
+
+FilePath FilePath::RemoveFinalExtension() const {
+  StringType extension = FinalExtension();
+  if (FinalExtension().empty())
+    return *this;
+  return FilePath(path_.substr(0, path_.size() - extension.size()));
+}
+
 FilePath FilePath::Append(const StringType& component) const {
   const StringType* appended = &component;
   StringType without_nuls;