chromeos: Remove NativeCursorManagerAshMus

It was only used with Config::MUS, which we don't support any more.

I left the base interface NativeCursorManagerAsh in case we need to
introduce a NativeCursorManagerMash later for Config::MASH.

Bug: 841941
Change-Id: Ia107cfbbcea0d52d2b2ada2f77c4017ab1bab8f7
Reviewed-on: https://chromium-review.googlesource.com/1080387
Commit-Queue: James Cook <jamescook@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563420}

ash/BUILD.gn

@@ -1071,8 +1071,6 @@ component("ash") {
     "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/non_client_frame_controller.cc",
     "wm/non_client_frame_controller.h",
     "wm/overlay_event_filter.cc",

ash/shell.cc

@@ -135,7 +135,6 @@
 #include "ash/wm/lock_state_controller.h"
 #include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/native_cursor_manager_ash_classic.h"
-#include "ash/wm/native_cursor_manager_ash_mus.h"
 #include "ash/wm/overlay_event_filter.h"
 #include "ash/wm/overview/window_selector_controller.h"
 #include "ash/wm/resize_shadow_controller.h"
@@ -1031,10 +1030,9 @@ void Shell::Init(ui::ContextFactory* context_factory,
     native_cursor_manager_ = new NativeCursorManagerAshClassic;
     cursor_manager_ = std::make_unique<CursorManager>(
         base::WrapUnique(native_cursor_manager_));
-  } else if (config == Config::MUS) {
-    native_cursor_manager_ = new NativeCursorManagerAshMus;
-    cursor_manager_ = std::make_unique<CursorManager>(
-        base::WrapUnique(native_cursor_manager_));
+  } else {
+    // TODO(jamescook|estade): Cursor manager for Config::MASH. We might be able
+    // to use most of the classic version after we switch to ws2.
   }
 
   shell_delegate_->PreInit();

ash/wm/native_cursor_manager_ash.h

@@ -16,6 +16,9 @@ namespace ash {
 // Ash specific extensions to NativeCursorManager. This lets us switch whether
 // we're using the native cursor, along with exposing additional data about how
 // we're going to render cursors.
+// TODO(jamescook): If we don't end up with a mash implementation of this
+// interface then collapse it with NativeCursorManagerAshClassic, which is the
+// only subclass.
 class ASH_EXPORT NativeCursorManagerAsh : public ::wm::NativeCursorManager {
  public:
   ~NativeCursorManagerAsh() override = default;