React to primary display change instead of removal

chrome/browser/chromeos/login/ui/login_display_host_impl.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 "chrome/browser/chromeos/login/ui/login_display_host_impl.h"
 
 #include <utility>
 #include <vector>
 
 #include "ash/public/cpp/shell_window_ids.h"
@@ skipping 963 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // LoginDisplayHostImpl, display::DisplayObserver:
 
 void LoginDisplayHostImpl::OnDisplayAdded(const display::Display& new_display) {
   if (GetOobeUI())
     GetOobeUI()->OnDisplayConfigurationChanged();
 }
 
 void LoginDisplayHostImpl::OnDisplayRemoved(
-    const display::Display& old_display) {
-  if (GetOobeUI())
-    GetOobeUI()->OnDisplayConfigurationChanged();
-}
+    const display::Display& old_display) {}

[oshima, 2017/05/17 16:56:18]

you can remove this

 
 void LoginDisplayHostImpl::OnDisplayMetricsChanged(
     const display::Display& display,
     uint32_t changed_metrics) {
   display::Display primary_display =
       display::Screen::GetScreen()->GetPrimaryDisplay();
   if (display.id() != primary_display.id() ||
       !(changed_metrics & DISPLAY_METRIC_BOUNDS)) {
     return;
   }
 
   if (GetOobeUI()) {
     const gfx::Size& size = primary_display.size();
     GetOobeUI()->GetCoreOobeView()->SetClientAreaSize(size.width(),
                                                       size.height());
+
+    if (changed_metrics & DISPLAY_METRIC_PRIMARY)
+      GetOobeUI()->OnDisplayConfigurationChanged();
   }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // LoginDisplayHostImpl, views::WidgetRemovalsObserver:
 void LoginDisplayHostImpl::OnWillRemoveView(views::Widget* widget,
                                             views::View* view) {
   if (view != static_cast<views::View*>(login_view_))
     return;
   login_view_ = nullptr;
@@ skipping 382 matching lines @@
   // Chrome locale. Otherwise it will be lost if Chrome restarts.
   // Don't need to schedule pref save because setting initial local
   // will enforce preference saving.
   prefs->SetString(prefs::kApplicationLocale, locale);
   StartupUtils::SetInitialLocale(locale);
 
   TriggerShowLoginWizardFinish(locale, std::move(data));
 }
 
 }  // namespace chromeos