mus: Implement interwindow drag and drop

services/ui/ws/server_window.h

 // Copyright 2014 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_SERVER_WINDOW_H_
 #define SERVICES_UI_WS_SERVER_WINDOW_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 68 matching lines @@
     return additional_client_areas_;
   }
   const gfx::Insets& client_area() const { return client_area_; }
   void SetClientArea(const gfx::Insets& insets,
                      const std::vector<gfx::Rect>& additional_client_areas);
 
   const gfx::Rect* hit_test_mask() const { return hit_test_mask_.get(); }
   void SetHitTestMask(const gfx::Rect& mask);
   void ClearHitTestMask();
 
+  bool can_accept_drags() const { return accepts_drags_; }
+  void SetCanAcceptDrags(bool accepts_drags);
+
   int32_t cursor() const { return static_cast<int32_t>(cursor_id_); }
   int32_t non_client_cursor() const {
     return static_cast<int32_t>(non_client_cursor_id_);
   }
 
   const ServerWindow* parent() const { return parent_; }
   ServerWindow* parent() { return parent_; }
 
   const ServerWindow* GetRoot() const;
   ServerWindow* GetRoot() {
@@ skipping 135 matching lines @@
   gfx::Vector2d underlay_offset_;
 
   // The hit test for windows extends outside the bounds of the window by this
   // amount.
   gfx::Insets extended_hit_test_region_;
 
   // Mouse events outside the hit test mask don't hit the window. An empty mask
   // means all events miss the window. If null there is no mask.
   std::unique_ptr<gfx::Rect> hit_test_mask_;
 
+  // Whether this window can be the target in a drag and drop
+  // operation. Clients must opt-in to this.
+  bool accepts_drags_ = false;
+
   base::ObserverList<ServerWindowObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(ServerWindow);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_SERVER_WINDOW_H_