Add ScreenPositionClient::ConvertNativePointToScreen.

ui/aura/client/screen_position_client.h

 // Copyright (c) 2012 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 UI_AURA_SCREEN_POSITION_CLIENT_H_
 #define UI_AURA_SCREEN_POSITION_CLIENT_H_
 
 #include "ui/aura/aura_export.h"
 #include "ui/aura/window.h"
 
@@ skipping 13 matching lines @@
 // An interface implemented by an object that changes coordinates on a
 // RootWindow into system coordinates.
 class AURA_EXPORT ScreenPositionClient {
  public:
   // Converts the |screen_point| from a given |window|'s coordinate space
   // into screen coordinate space.
   virtual void ConvertPointToScreen(const Window* window,
                                     gfx::Point* point) = 0;
   virtual void ConvertPointFromScreen(const Window* window,
                                       gfx::Point* point) = 0;
+  // Converts the |screen_point| from a given |window|'s native screen
+  // coordinate space into screen coordinate space.
+  // A typical example of using this function instead of ConvertPointToScreen is
+  // when X's native input is captured by a drag operation.
+  // See the comments in ash::wm::GetRootWindowRelativeToWindow for details.

[oshima, 2012/09/18 10:02:34]

This description isn't exactly correct, i think. 
This is to convert an event whose location is outside of
the mouse event target's root (mouse_moved_handler_ i believe). Passive grab is
one scenario and aura capture is another scenario. (see my comment in
coordinate_conversion.cc)

[mazda, 2012/09/18 16:35:01]

I'm thinking about letting this function handle only passive grab case because
trying to handle another scenario causes problems when bounds in native and
scree overlaps as we talked before.

+  virtual void ConvertNativePointToScreen(Window* window,
+                                          gfx::Point* point) = 0;
   // Sets the bounds of the window. The implementation is responsible
   // for finding out and translating the right coordinates for the |window|.
   virtual void SetBounds(Window* window,
                          const gfx::Rect& bounds,
                          const gfx::Display& display) = 0;
   virtual ~ScreenPositionClient() {}
 };
 
 // Sets/Gets the activation client on the Window.
 AURA_EXPORT void SetScreenPositionClient(RootWindow* window,
                                          ScreenPositionClient* client);
 AURA_EXPORT ScreenPositionClient* GetScreenPositionClient(
     const RootWindow* window);
 
 }  // namespace clients
 }  // namespace aura
 
 #endif  // UI_AURA_SCREEN_POSITION_CLIENT_H_