mus: Implement interwindow drag and drop

services/ui/public/cpp/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_PUBLIC_CPP_WINDOW_H_
 #define SERVICES_UI_PUBLIC_CPP_WINDOW_H_
 
 #include <stdint.h>
 #include <vector>
 
@@ skipping 12 matching lines @@
 class Size;
 }
 
 namespace ui {
 
 class InputEventHandler;
 class ServiceProviderImpl;
 class WindowObserver;
 class WindowSurface;
 class WindowSurfaceBinding;
+class WindowDropTarget;
 class WindowTreeClient;
 class WindowTreeClientPrivate;
 
 namespace {
 class OrderChangedNotifier;
 }
 
 // Defined in window_property.h (which we do not include)
 template <typename T>
 struct WindowProperty;
@@ skipping 159 matching lines @@
 
   bool HasCapture() const;
   void SetCapture();
   void ReleaseCapture();
 
   // Focus. See WindowTreeClient::ClearFocus() to reset focus.
   void SetFocus();
   bool HasFocus() const;
   void SetCanFocus(bool can_focus);
 
+  // Sets whether this window accepts drags. Passing a non-null |drop_target|
+  // will enable acceptance of drops. Passing null will disable it.
+  void SetCanAcceptDrops(WindowDropTarget* drop_target);
+  WindowDropTarget* drop_target() const { return drop_target_; }

[sky, 2016/09/13 18:15:31]

Either return const here, or remove const from signature.

+
   // Sets whether this window accepts events.
   void SetCanAcceptEvents(bool can_accept_events);
 
   // Embedding. See window_tree.mojom for details.
   void Embed(ui::mojom::WindowTreeClientPtr client, uint32_t flags = 0);
 
   // NOTE: callback is run synchronously if Embed() is not allowed on this
   // Window.
   void Embed(ui::mojom::WindowTreeClientPtr client,
              const EmbedCallback& callback,
              uint32_t flags = 0);
 
   // TODO(sky): this API is only applicable to the WindowManager. Move it
   // to a better place.
   void RequestClose();
 
+  // Starts an inter-process drag and drop operation.
+  void PerformDragDrop(
+      int drag_pointer,
+      const std::map<std::string, std::vector<uint8_t>>& drag_data,
+      int drag_operation,
+      const gfx::Point& cursor_location,
+      const SkBitmap& bitmap,
+      const base::Callback<void(bool)>& callback);
+
   // Tells the window manager to take control of moving the window. Returns
   // true if the move wasn't canceled.
   void PerformWindowMove(mojom::MoveLoopSource source,
                          const gfx::Point& cursor_location,
                          const base::Callback<void(bool)>& callback);
 
   // Tells the window manager to abort any current move initiated by
   // PerformWindowMove().
   void CancelWindowMove();
 
@@ skipping 97 matching lines @@
 
   gfx::Rect bounds_;
   gfx::Insets client_area_;
   std::vector<gfx::Rect> additional_client_areas_;
   std::unique_ptr<gfx::Rect> hit_test_mask_;
 
   bool visible_;
   float opacity_;
   int64_t display_id_;
 
+  // The client supplied delegate that receives drag events for this
+  // window (weak ptr).
+  WindowDropTarget* drop_target_ = nullptr;
+
   // Whether this window can accept events. Initialized to true to
   // match ServerWindow.
   bool can_accept_events_ = true;
 
   mojom::Cursor cursor_id_;
 
   SharedProperties properties_;
 
   // Drawn state of our parent. This is only meaningful for root Windows, in
   // which the parent Window isn't exposed to the client.
   bool parent_drawn_;
 
   // Value struct to keep the name and deallocator for this property.
   // Key cannot be used for this purpose because it can be char* or
   // WindowProperty<>.
   struct Value {
     const char* name;
     int64_t value;
     PropertyDeallocator deallocator;
   };
 
   std::map<const void*, Value> prop_map_;
 
   DISALLOW_COPY_AND_ASSIGN(Window);
 };
 
 }  // namespace ui
 
 #endif  // SERVICES_UI_PUBLIC_CPP_WINDOW_H_