Revert of Moving coordinate conversion methods from ash/wm to ui/wm.

ash/wm/coordinate_conversion.cc

Index: ash/wm/coordinate_conversion.cc
diff --git a/ash/wm/coordinate_conversion.cc b/ash/wm/coordinate_conversion.cc
index 258f97664aca5c1d0addf79ead40efc501a60bc5..991e7d4e1a0d4f4a73b01fdcc155de8ee9186992 100644
--- a/ash/wm/coordinate_conversion.cc
+++ b/ash/wm/coordinate_conversion.cc
@@ -31,5 +31,17 @@
       GetRootWindowForDisplayId(display.id());
 }
 
+void ConvertPointToScreen(const aura::Window* window, gfx::Point* point) {
+  CHECK(aura::client::GetScreenPositionClient(window->GetRootWindow()));
+  aura::client::GetScreenPositionClient(window->GetRootWindow())->
+      ConvertPointToScreen(window, point);
+}
+
+void ConvertPointFromScreen(const aura::Window* window,
+                            gfx::Point* point_in_screen) {
+  aura::client::GetScreenPositionClient(window->GetRootWindow())->
+      ConvertPointFromScreen(window, point_in_screen);
+}
+
 }  // namespace wm
 }  // namespace ash