mus: Implement interwindow drag and drop

services/ui/ws/current_drag_operation.h

Index: services/ui/ws/current_drag_operation.h
diff --git a/services/ui/ws/current_drag_operation.h b/services/ui/ws/current_drag_operation.h
new file mode 100644
index 0000000000000000000000000000000000000000..87570cd160b695790e6dac2eab054c35128b12b7
--- /dev/null
+++ b/services/ui/ws/current_drag_operation.h
@@ -0,0 +1,89 @@
+// 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 SERVICES_UI_WS_CURRENT_DRAG_OPERATION_H_
+#define SERVICES_UI_WS_CURRENT_DRAG_OPERATION_H_
+
+#include <deque>
+
+#include "base/memory/weak_ptr.h"
+#include "services/ui/common/types.h"
+#include "services/ui/ws/ids.h"
+#include "services/ui/ws/server_window_observer.h"
+
+namespace ui {
+namespace ws {
+
+class CurrentDragOperationDelegate;
+class WindowServer;
+class WindowTree;
+
+// Represents all the data around the current ongoing drag operation.
+//
+// There should only be one instance of this class per userid
+class CurrentDragOperation : public ServerWindowObserver {
+ public:
+  CurrentDragOperation(CurrentDragOperationDelegate* delegate,
+                       uint32_t change_id,
+                       WindowTree* source_window_tree,
+                       ServerWindow* source_window,
+                       mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data,
+                       uint32_t drag_operations);
+  ~CurrentDragOperation() override;
+
+  void DispatchLocatedEvent(const ui::LocatedEvent& event,
+                            ServerWindow* current_target,
+                            const ClientSpecificId& client_id);
+
+  void MessageDragCompleted(bool success);
+
+ private:
+  struct Operation;
+
+  void DispatchFrontOfWindowQueue(ServerWindow* window,
+                                  std::deque<Operation>* queue);
+
+  // Overridden from ServerWindowObserver:
+  void OnWindowDestroying(ServerWindow* window) override;
+
+  // Callback methods.
+  void OnDragStatusCompleted(const WindowId& id, uint32_t bitmask);
+  void OnDragDropCompleted(const WindowId& id, uint32_t bitmask);
+
+  // Our owner.
+  CurrentDragOperationDelegate* delegate_ = nullptr;
+
+  uint32_t change_id_;
+
+  uint32_t drag_operations_;
+
+  bool waiting_for_final_drop_response_ = false;
+
+  WindowTree* source_window_tree_ = nullptr;
+
+  WindowServer* window_server_ = nullptr;
+
+  // The window which started the drag and which acts as the ipc source.
+  ServerWindow* source_window_ = nullptr;
+
+  ServerWindow* current_target_window_ = nullptr;
+
+  // A list of the offered mime types.
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data_;
+
+  // Event queues for each window. If a vector is empty, there are no
+  // operations going on. If a vector has one operation, we're waiting on a
+  // response for that operation from the client. Every operation past the
+  // first is queued.
+  std::map<ServerWindow*, std::deque<Operation>> current_window_state_;
+
+  base::WeakPtrFactory<CurrentDragOperation> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(CurrentDragOperation);
+};
+
+}  // namespace ws
+}  // namespace ui
+
+#endif  // SERVICES_UI_WS_CURRENT_DRAG_OPERATION_H_