[InputEvent] Support |deleteByDrag|, |insertFromDrop| and fire in sequential order

third_party/WebKit/Source/core/editing/commands/DragAndDropCommand.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef DragAndDropCommand_h
+#define DragAndDropCommand_h
+
+#include "core/editing/commands/CompositeEditCommand.h"
+
+namespace blink {
+
+// |DragAndDropCommand| is a dummy command. It doesn't do anything by itself,
+// but will act as a catcher for the following |DeleteByDrag| and
+// |InsertFromDrop| commands, and combine them into a single undo entry.
+// In the future when necessary, this mechanism can be generalized into a common
+// command wrapper to achieve undo group.
+class DragAndDropCommand final : public CompositeEditCommand {
+ public:
+  static DragAndDropCommand* create(Document& document) {
+    return new DragAndDropCommand(document);
+  }
+
+  bool isCommandGroupWrapper() const override;
+  bool isDragAndDropCommand() const override;
+
+ private:
+  explicit DragAndDropCommand(Document&);
+
+  void doApply(EditingState*) override;
+  InputEvent::InputType inputType() const override;
+};
+
+}  // namespace blink
+
+#endif  // DragAndDropCommand_h