mus: Implement ScreenMus::GetCursorScreenPoint().

components/mus/ws/window_manager_state.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 COMPONENTS_MUS_WS_WINDOW_MANAGER_STATE_H_
 #define COMPONENTS_MUS_WS_WINDOW_MANAGER_STATE_H_
 
 #include <stdint.h>
 
+#include "base/atomicops.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/timer/timer.h"
 #include "components/mus/public/interfaces/display.mojom.h"
 #include "components/mus/ws/event_dispatcher.h"
 #include "components/mus/ws/event_dispatcher_delegate.h"
 #include "components/mus/ws/user_id.h"
 #include "components/mus/ws/window_server.h"
 
 namespace cc {
@@ skipping 79 matching lines @@
   // received.
   // TODO(sky): make this private and use a callback.
   void OnEventAck(mojom::WindowTree* tree, mojom::EventResult result);
 
   // Returns a mojom::Display for the specified display. WindowManager specific
   // values are not set.
   mojom::DisplayPtr ToMojomDisplay() const;
 
   void OnWillDestroyTree(WindowTree* tree);
 
+  mojo::ScopedSharedBufferHandle GetCursorLocationMemory();
+
  private:
   class ProcessedEventTarget;
   friend class Display;
   friend class test::WindowManagerStateTestApi;
 
   // There are two types of events that may be queued, both occur only when
   // waiting for an ack from a client.
   // . We get an event from the PlatformDisplay. This results in |event| being
   //   set, but |processed_target| is null.
   // . We get an event from the EventDispatcher. In this case both |event| and
@@ skipping 33 matching lines @@
                                       const ui::Event& event,
                                       base::WeakPtr<Accelerator> accelerator);
 
   // EventDispatcherDelegate:
   void OnAccelerator(uint32_t accelerator_id, const ui::Event& event) override;
   void SetFocusedWindowFromEventDispatcher(ServerWindow* window) override;
   ServerWindow* GetFocusedWindowForEventDispatcher() override;
   void SetNativeCapture() override;
   void ReleaseNativeCapture() override;
   void OnServerWindowCaptureLost(ServerWindow* window) override;
+  void OnMouseCursorLocationChanged(const gfx::Point& point) override;
   void DispatchInputEventToWindow(ServerWindow* target,
                                   bool in_nonclient_area,
                                   const ui::Event& event,
                                   Accelerator* accelerator) override;
 
   Display* display_;
   PlatformDisplay* platform_display_;
   // If this was created implicitly by a call
   // WindowTreeHostFactory::CreateWindowTreeHost(), then |is_user_id_valid_|
   // is false.
   const bool is_user_id_valid_;
   const UserId user_id_;
   // Root ServerWindow of this WindowManagerState. |root_| has a parent, the
   // root ServerWindow of the Display.
   scoped_ptr<ServerWindow> root_;
   WindowTree* tree_ = nullptr;
 
   // Set to true the first time SetFrameDecorationValues() is received.
   bool got_frame_decoration_values_ = false;
   mojom::FrameDecorationValuesPtr frame_decoration_values_;
 
   mojom::WindowTree* tree_awaiting_input_ack_ = nullptr;
   scoped_ptr<ui::Event> event_awaiting_input_ack_;
   base::WeakPtr<Accelerator> post_target_accelerator_;
   std::queue<scoped_ptr<QueuedEvent>> event_queue_;
   base::OneShotTimer event_ack_timer_;
 
   EventDispatcher event_dispatcher_;
 
+  // The current location of the cursor. This is always kept up to date so we
+  // can atomically write this to |cursor_location_memory_| once it is created.
+  base::subtle::Atomic64 current_cursor_location_;
+
+  // A handle to a shared memory buffer that is one 64 bit integer long. We
+  // share this with any connection as the same user. This buffer is lazily
+  // created on the first access.
+  mojo::ScopedSharedBufferHandle cursor_location_handle_;
+
+  // The one int64 in |cursor_location_handle_|. When we write to this
+  // location, we must always write to it atomically. (On the other side of the
+  // mojo connection, this data must be read atomically.)
+  base::subtle::Atomic64* cursor_location_memory_;
+
   DISALLOW_COPY_AND_ASSIGN(WindowManagerState);
 };
 
 }  // namespace ws
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_WS_WINDOW_MANAGER_STATE_H_