Implement cursor changing on Mushrome

ash/BUILD.gn

Index: ash/BUILD.gn
diff --git a/ash/BUILD.gn b/ash/BUILD.gn
index 3f00c346b0a81ce218ba15a3542b00a7434fcb4f..abe07eae69a72bc7a0d025813c4222c5195c6bdc 100644
--- a/ash/BUILD.gn
+++ b/ash/BUILD.gn
@@ -625,8 +625,6 @@ component("ash") {
     "wm/always_on_top_controller.h",
     "wm/ash_focus_rules.cc",
     "wm/ash_focus_rules.h",
-    "wm/ash_native_cursor_manager.cc",
-    "wm/ash_native_cursor_manager.h",
     "wm/boot_splash_screen_chromeos.cc",
     "wm/boot_splash_screen_chromeos.h",
     "wm/container_finder.cc",
@@ -687,6 +685,11 @@ component("ash") {
     "wm/maximize_mode/scoped_disable_internal_mouse_and_keyboard_x11.h",
     "wm/mru_window_tracker.cc",
     "wm/mru_window_tracker.h",
+    "wm/native_cursor_manager_ash.h",
+    "wm/native_cursor_manager_ash_classic.cc",
+    "wm/native_cursor_manager_ash_classic.h",
+    "wm/native_cursor_manager_ash_mus.cc",
+    "wm/native_cursor_manager_ash_mus.h",
     "wm/overlay_event_filter.cc",
     "wm/overlay_event_filter.h",
     "wm/overview/cleanup_animation_observer.cc",
@@ -1393,7 +1396,7 @@ test("ash_unittests") {
     "wm/always_on_top_controller_unittest.cc",
 
     # TODO: mash doesn't support CursorManager. http://crbug.com/631103.
-    "wm/ash_native_cursor_manager_unittest.cc",
+    "wm/native_cursor_manager_ash_unittest.cc",
 
     # TODO: mash doesn't support DragWindowResizer. http://crbug.com/633782.
     "wm/drag_window_resizer_unittest.cc",