Makes SetFocus() notify callback correctly on failure

components/mus/ws/display.cc

 // Copyright 2015 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 "components/mus/ws/display.h"
 
 #include "base/debug/debugger.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/mus/common/types.h"
 #include "components/mus/ws/display_binding.h"
@@ skipping 139 matching lines @@
 
 mojom::Rotation Display::GetRotation() const {
   return platform_display_->GetRotation();
 }
 
 const WindowManagerState* Display::GetActiveWindowManagerState() const {
   return GetWindowManagerStateForUser(
       window_server_->user_id_tracker()->active_id());
 }
 
-void Display::SetFocusedWindow(ServerWindow* new_focused_window) {
+bool Display::SetFocusedWindow(ServerWindow* new_focused_window) {
   ServerWindow* old_focused_window = focus_controller_->GetFocusedWindow();
   if (old_focused_window == new_focused_window)
-    return;
+    return true;
   DCHECK(!new_focused_window || root_window()->Contains(new_focused_window));
-  focus_controller_->SetFocusedWindow(new_focused_window);
+  return focus_controller_->SetFocusedWindow(new_focused_window);
 }
 
 ServerWindow* Display::GetFocusedWindow() {
   return focus_controller_->GetFocusedWindow();
 }
 
 void Display::ActivateNextWindow() {
   // TODO(sky): this is wrong, needs to figure out the next window to activate
   // and then route setting through WindowServer.
   focus_controller_->ActivateNextWindow();
@@ skipping 305 matching lines @@
   DCHECK_EQ(0u, window_manager_state_map_.count(id));
 }
 
 void Display::OnWindowManagerFactorySet(WindowManagerFactoryService* service) {
   if (!binding_)
     CreateWindowManagerStateFromService(service);
 }
 
 }  // namespace ws
 }  // namespace mus