Keep root_location to be in pixels and display coordinates in WS.

services/ui/ws/event_dispatcher_delegate.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 SERVICES_UI_WS_EVENT_DISPATCHER_DELEGATE_H_
 #define SERVICES_UI_WS_EVENT_DISPATCHER_DELEGATE_H_
 
 #include <stdint.h>
 
 #include "services/ui/common/types.h"
@@ skipping 37 matching lines @@
   // Called when EventDispatcher has a new value for the cursor and our
   // delegate should perform the native updates.
   virtual void UpdateNativeCursorFromDispatcher() = 0;
 
   // Called when |window| has lost capture. The native display may still be
   // holding capture. The delegate should not change native display capture.
   // ReleaseNativeCapture() is invoked if appropriate.
   virtual void OnCaptureChanged(ServerWindow* new_capture,
                                 ServerWindow* old_capture) = 0;
 
-  virtual void OnMouseCursorLocationChanged(const gfx::Point& point) = 0;
+  virtual void OnMouseCursorLocationChanged(const gfx::Point& point,
+                                            const int64_t display_id) = 0;
 
   // Dispatches an event to the specific client.
   virtual void DispatchInputEventToWindow(ServerWindow* target,
                                           ClientSpecificId client_id,
                                           const ui::Event& event,
                                           Accelerator* accelerator) = 0;
 
   // Returns the id of the client to send events to. |in_nonclient_area| is
   // true if the event occurred in the non-client area of the window.
   virtual ClientSpecificId GetEventTargetClientId(const ServerWindow* window,
                                                   bool in_nonclient_area) = 0;
 
   // Returns the window to start searching from at the specified location, or
-  // null if there is a no window containing |location|. |location| should be in
-  // screen coordinates and if a window is returned then |location| will be
-  // updated to be relative to the origin of the window.
-  virtual ServerWindow* GetRootWindowContaining(gfx::Point* location) = 0;
+  // null if there is a no window containing |location_in_display|.
+  // |location_in_display| should be in display coordinates and in pixels.
+  // |location_in_display| and |display_id| will be updated if the window we
+  // found is on a different display than the originated display.
+  virtual ServerWindow* GetRootWindowContaining(gfx::Point* location_in_display,
+                                                int64_t* display_id) = 0;
 
   // Called when event dispatch could not find a target. OnAccelerator may still
   // be called.
   virtual void OnEventTargetNotFound(const ui::Event& event) = 0;
 
  protected:
   virtual ~EventDispatcherDelegate() {}
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_EVENT_DISPATCHER_DELEGATE_H_