mus: Let clients set the cursor of their window.

components/mus/ws/event_dispatcher.h

 // Copyright 2015 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 COMPONENTS_MUS_WS_EVENT_DISPATCHER_H_
 #define COMPONENTS_MUS_WS_EVENT_DISPATCHER_H_
 
 #include <map>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 15 matching lines @@
 // Handles dispatching events to the right location as well as updating focus.
 class EventDispatcher : public ServerWindowObserver {
  public:
   explicit EventDispatcher(EventDispatcherDelegate* delegate);
   ~EventDispatcher() override;
 
   void set_root(ServerWindow* root) { root_ = root; }
 
   void set_surface_id(cc::SurfaceId surface_id) { surface_id_ = surface_id; }
 
+  // Retrieves the ServerWindow of the last mouse move.
+  ServerWindow* mouse_cursor_source_window() const {
+    return mouse_cursor_source_window_;
+  }
+
   // Adds an accelerator with the given id and event-matcher. If an accelerator
   // already exists with the same id or the same matcher, then the accelerator
   // is not added. Returns whether adding the accelerator was successful or not.
   bool AddAccelerator(uint32_t id, mojom::EventMatcherPtr event_matcher);
   void RemoveAccelerator(uint32_t id);
 
   void OnEvent(mojom::EventPtr event);
 
  private:
   // Keeps track of state associated with a pointer down until the
@@ skipping 42 matching lines @@
   // ServerWindowObserver:
   void OnWillChangeWindowHierarchy(ServerWindow* window,
                                    ServerWindow* new_parent,
                                    ServerWindow* old_parent) override;
   void OnWindowVisibilityChanged(ServerWindow* window) override;
   void OnWindowDestroyed(ServerWindow* window) override;
 
   EventDispatcherDelegate* delegate_;
   ServerWindow* root_;
 
+  bool mouse_button_down_;
+  ServerWindow* mouse_cursor_source_window_;
+
   cc::SurfaceId surface_id_;
 
   using Entry = std::pair<uint32_t, EventMatcher>;
   std::map<uint32_t, EventMatcher> accelerators_;
 
   using PointerIdToTargetMap = std::map<int32_t, PointerTarget>;
   PointerIdToTargetMap pointer_targets_;
 
   DISALLOW_COPY_AND_ASSIGN(EventDispatcher);
 };
 
 }  // namespace ws
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_WS_EVENT_DISPATCHER_H_