DataTransfer: Make |types| be a FrozenArray<DOMString>.

third_party/WebKit/Source/core/clipboard/DataTransfer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 174 matching lines @@
   return ConvertURIListToURL(data);
 }
 
 void DataTransfer::setData(const String& type, const String& data) {
   if (!CanWriteData())
     return;
 
   data_object_->SetData(NormalizeType(type), data);
 }
 
-// extensions beyond IE's API
-Vector<String> DataTransfer::types() const {
+bool DataTransfer::hasDataStoreItemListChanged() const {
+  return data_store_item_list_changed_ || !CanReadTypes();
+}
+
+void DataTransfer::OnItemListChanged() {
+  data_store_item_list_changed_ = true;
+}
+
+Vector<String> DataTransfer::types() {
   Vector<String> types;
   if (!CanReadTypes())
     return types;

[jsbell, 2017/05/15 20:49:28]

Not new in this CL, but how about `return Vector<String>();` here and remove the
`types` local?

[Raphael Kubo da Costa (rakuco), 2017/05/16 08:51:51]

Done.

 
+  data_store_item_list_changed_ = false;
   return data_object_->Types();
 }
 
 FileList* DataTransfer::files() const {
   FileList* files = FileList::Create();
   if (!CanReadData())
     return files;
 
   for (size_t i = 0; i < data_object_->length(); ++i) {
     if (data_object_->Item(i)->Kind() == DataObjectItem::kFileKind) {
@@ skipping 211 matching lines @@
   return data_object_;
 }
 
 DataTransfer::DataTransfer(DataTransferType type,
                            DataTransferAccessPolicy policy,
                            DataObject* data_object)
     : policy_(policy),
       drop_effect_("uninitialized"),
       effect_allowed_("uninitialized"),
       transfer_type_(type),
-      data_object_(data_object) {}
+      data_object_(data_object),
+      data_store_item_list_changed_(true) {
+  data_object_->AddObserver(this);
+}
 
 void DataTransfer::setDragImage(ImageResourceContent* image,
                                 Node* node,
                                 const IntPoint& loc) {
   if (!CanSetDragImage())
     return;
 
   drag_image_ = image;
   drag_loc_ = loc;
   drag_image_element_ = node;
@@ skipping 11 matching lines @@
         return true;
     }
   }
   return false;
 }
 
 bool DataTransfer::HasStringOfType(const String& type) const {
   if (!CanReadTypes())
     return false;
 
-  return types().Contains(type);
+  return data_object_->Types().Contains(type);
 }
 
 DragOperation ConvertDropZoneOperationToDragOperation(
     const String& drag_operation) {
   if (drag_operation == "copy")
     return kDragOperationCopy;
   if (drag_operation == "move")
     return kDragOperationMove;
   if (drag_operation == "link")
     return kDragOperationLink;
@@ skipping 13 matching lines @@
   }
 }
 
 DEFINE_TRACE(DataTransfer) {
   visitor->Trace(data_object_);
   visitor->Trace(drag_image_);
   visitor->Trace(drag_image_element_);
 }
 
 }  // namespace blink