Fix WindowTreeClient::RequestClose(window_id).

ui/aura/mus/window_tree_client.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 "ui/aura/mus/window_tree_client.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
@@ skipping 1293 matching lines @@
 
 void WindowTreeClient::GetWindowManager(
     mojo::AssociatedInterfaceRequest<WindowManager> internal) {
   window_manager_internal_.reset(
       new mojo::AssociatedBinding<ui::mojom::WindowManager>(
           this, std::move(internal)));
 }
 
 void WindowTreeClient::RequestClose(uint32_t window_id) {
   WindowMus* window = GetWindowByServerId(window_id);
-  if (!window || !IsRoot(window))
+  if (!window)
     return;
 
-  window->GetWindow()->delegate()->OnRequestClose();
+  // If the window is the root window, we send close request to the entire
+  // WindowTreeHost. Otherwise we ask the delegate of the window to close it.
+  if (IsRoot(window)) {
+    GetWindowTreeHostMus(window->GetWindow())->OnCloseRequest();
+  } else {
+    window->GetWindow()->delegate()->OnRequestClose();
+  }

[sadrul, 2017/01/04 20:08:07]

Don't need {}

As discussed offline, the alternate is to use a delegate when creating the
root-window for the WTHostMus, and close the WTH from its OnRequestClose()
override. However, doing that would cause aura::Window::GetToplevelWindow() to
always return the root-window, which may not be what we want. So special-casing
the root window here seems like the better solution.

+sky@ for thoughts.

 }
 
 void WindowTreeClient::OnConnect(ClientSpecificId client_id) {
   client_id_ = client_id;
 }
 
 void WindowTreeClient::WmNewDisplayAdded(const display::Display& display,
                                          ui::mojom::WindowDataPtr root_data,
                                          bool parent_drawn) {
   WmNewDisplayAddedImpl(display, std::move(root_data), parent_drawn);
@@ skipping 364 matching lines @@
   return ScheduleInFlightChange(base::MakeUnique<InFlightCaptureChange>(
       this, capture_synchronizer_.get(), window));
 }
 
 uint32_t WindowTreeClient::CreateChangeIdForFocus(WindowMus* window) {
   return ScheduleInFlightChange(base::MakeUnique<InFlightFocusChange>(
       this, focus_synchronizer_.get(), window));
 }
 
 }  // namespace aura