Add the "virtual" keyword on method overrides that are missing it.

webkit/glue/plugins/pepper_directory_reader.cc

Index: webkit/glue/plugins/pepper_directory_reader.cc
diff --git a/webkit/glue/plugins/pepper_directory_reader.cc b/webkit/glue/plugins/pepper_directory_reader.cc
index c476b76296a5a315f3911caf2a4f51f343ddb813..9f7b8197be183faf9c3154e03593bf3d6ef43757 100644
--- a/webkit/glue/plugins/pepper_directory_reader.cc
+++ b/webkit/glue/plugins/pepper_directory_reader.cc
@@ -89,6 +89,10 @@ const PPB_DirectoryReader_Dev* DirectoryReader::GetInterface() {
   return &ppb_directoryreader;
 }
 
+DirectoryReader* DirectoryReader::AsDirectoryReader() {
+  return this;
+}
+
 int32_t DirectoryReader::GetNextEntry(PP_DirectoryEntry_Dev* entry,
                                       PP_CompletionCallback callback) {
   if (directory_ref_->GetFileSystemType() == PP_FILESYSTEMTYPE_EXTERNAL)