MacViews: Implement Tab Dragging

ui/views/cocoa/cocoa_window_move_loop.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 UI_VIEWS_COCOA_COCOA_WINDOW_MOVE_LOOP_H_
+#define UI_VIEWS_COCOA_COCOA_WINDOW_MOVE_LOOP_H_
+
+#import <Cocoa/Cocoa.h>
+
+#include "base/callback.h"
+#include "base/memory/weak_ptr.h"
+#include "ui/views/widget/widget.h"
+
+namespace views {
+class BridgedNativeWidget;
+
+// Used by views::BridgedNativeWidget when dragging detached tabs.
+class CocoaWindowMoveLoop {
+ public:
+  CocoaWindowMoveLoop(BridgedNativeWidget* owner,
+                      const NSPoint& initial_mouse_in_screen);
+  ~CocoaWindowMoveLoop();
+
+  // Initiates the drag until a mouse up event is observed, or End() is called.
+  Widget::MoveLoopResult Run();
+  void End();
+
+ private:
+  enum LoopExitReason {
+    ENDED_EXTERNALLY,
+    MOUSE_UP,
+    WINDOW_DESTROYED,
+  };
+
+  BridgedNativeWidget* owner_;  // Weak. Owns this.
+
+  // Initial mouse location at the time before the CocoaWindowMoveLoop is
+  // created.
+  NSPoint initial_mouse_in_screen_;
+
+  // Pointer to a stack variable holding the exit reason.
+  LoopExitReason* exit_reason_ref_ = nullptr;
+  base::Closure quit_closure_;
+
+  // WeakPtrFactory for event monitor safety.
+  base::WeakPtrFactory<CocoaWindowMoveLoop> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(CocoaWindowMoveLoop);
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_COCOA_COCOA_WINDOW_MOVE_LOOP_H_