aura-mus: Make StackAtTop() proxy to the window manager.

services/ui/ws/window_tree_client_unittest.cc

 // Copyright 2014 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.
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
@@ skipping 458 matching lines @@
     NOTIMPLEMENTED();
   }
   void WmPerformMoveLoop(uint32_t change_id,
                          uint32_t window_id,
                          mojom::MoveLoopSource source,
                          const gfx::Point& cursor_location) override {
     NOTIMPLEMENTED();
   }
   void WmCancelMoveLoop(uint32_t window_id) override { NOTIMPLEMENTED(); }
   void WmDeactivateWindow(uint32_t window_id) override { NOTIMPLEMENTED(); }
+  void WmStackAtTop(uint32_t change_id, uint32_t window_id) override {
+    NOTIMPLEMENTED();
+  }
   void OnAccelerator(uint32_t ack_id,
                      uint32_t accelerator_id,
                      std::unique_ptr<ui::Event> event) override {
     NOTIMPLEMENTED();
   }
 
   TestChangeTracker tracker_;
 
   mojom::WindowTreePtr tree_;
 
@@ skipping 1726 matching lines @@
 
 // TODO(sky): make sure coverage of what was
 // WindowManagerTest.SecondEmbedRoot_InitService and
 // WindowManagerTest.MultipleEmbedRootsBeforeWTHReady gets added to window
 // manager
 // tests.
 
 }  // namespace test
 }  // namespace ws
 }  // namespace ui