Makes display roots be destroyed by client

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/message_loop/message_loop.h"
@@ skipping 406 matching lines @@
         GetProxy(&window_manager_client_, tree_.associated_group()));
   }
 
   // mojom::WindowManager:
   void OnConnect(uint16_t client_id) override {}
   void WmNewDisplayAdded(const display::Display& display,
                          mojom::WindowDataPtr root_data,
                          bool drawn) override {
     NOTIMPLEMENTED();
   }
+  void WmDisplayRemoved(int64_t display_id) override { NOTIMPLEMENTED(); }
   void WmSetBounds(uint32_t change_id,
                    uint32_t window_id,
                    const gfx::Rect& bounds) override {
     window_manager_client_->WmResponse(change_id, false);
   }
   void WmSetProperty(uint32_t change_id,
                      uint32_t window_id,
                      const mojo::String& name,
                      mojo::Array<uint8_t> value) override {
     window_manager_client_->WmResponse(change_id, false);
@@ skipping 1673 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