Support creation of toplevel mus::Windows on separate displays

ash/mus/bridge/wm_root_window_controller_mus.h

Index: ash/mus/bridge/wm_root_window_controller_mus.h
diff --git a/ash/mus/bridge/wm_root_window_controller_mus.h b/ash/mus/bridge/wm_root_window_controller_mus.h
index ebc5ac3eeb4fc2a37a790740b1b8bace579c53dc..02c613389fde854dffb0a008aca537c91f6e7f56 100644
--- a/ash/mus/bridge/wm_root_window_controller_mus.h
+++ b/ash/mus/bridge/wm_root_window_controller_mus.h
@@ -40,6 +40,9 @@ class WmRootWindowControllerMus : public WmRootWindowController {
     return root_window_controller_;
   }
 
+  gfx::Rect* ConvertWindowToScreen(const WmWindowMus* source,

[mfomitchev, 2016/11/17 17:14:01]

Doesn't seem like there's any reason to create a method for this here. Can we
just do the calculations in NewTopLevelWindow? Also, perhaps it would be more
convenient to use WmWindow::ConvertPointToScreen rather than
WmRootWindowControllerMus?

Also, we are leaking the rect - it is created on the heap and never deleted.
Just use an object, not an object pointer.

[thanhph, 2016/11/17 19:08:30]

Putting this function here could be good for future reuse. I'll move it back to
root_window_controller.cc since there's no other use of it now. I tried this
WmWindow::ConvertPointToScreen the whole day yesterday but didn't work. The
problem was somehow WmWindow wasn't initialized and as a result, I kept getting
ASAN:DEADLYSIGNAL. 
Thanks. I'll try this now.

+                                   const ui::Window* window) const;
+
   // Screen conversion functions.
   gfx::Point ConvertPointToScreen(const WmWindowMus* source,
                                   const gfx::Point& point) const;