Reland of Use a standard message box for DesktopCastingWarningView.

components/constrained_window/constrained_window_views.cc

 // Copyright (c) 2012 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/constrained_window/constrained_window_views.h"
 
 #include <algorithm>
 
 #include "base/macros.h"
 #include "build/build_config.h"
@@ skipping 10 matching lines @@
 #if defined(OS_MACOSX)
 #import "components/constrained_window/native_web_contents_modal_dialog_manager_views_mac.h"
 #endif
 
 using web_modal::ModalDialogHost;
 using web_modal::ModalDialogHostObserver;
 
 namespace constrained_window {
 namespace {
 
-ConstrainedWindowViewsClient* constrained_window_views_client = NULL;
+ConstrainedWindowViewsClient* constrained_window_views_client = nullptr;
 
 // The name of a key to store on the window handle to associate
 // WidgetModalDialogHostObserverViews with the Widget.
 const char* const kWidgetModalDialogHostObserverViewsKey =
     "__WIDGET_MODAL_DIALOG_HOST_OBSERVER_VIEWS__";
 
 // Applies positioning changes from the ModalDialogHost to the Widget.
 class WidgetModalDialogHostObserverViews
     : public views::WidgetObserver,
       public ModalDialogHostObserver {
  public:
   WidgetModalDialogHostObserverViews(ModalDialogHost* host,
                                      views::Widget* target_widget,
                                      const char *const native_window_property)
       : host_(host),
         target_widget_(target_widget),
         native_window_property_(native_window_property) {
     DCHECK(host_);
     DCHECK(target_widget_);
     host_->AddObserver(this);
     target_widget_->AddObserver(this);
   }
 
   ~WidgetModalDialogHostObserverViews() override {
     if (host_)
       host_->RemoveObserver(this);
     target_widget_->RemoveObserver(this);
-    target_widget_->SetNativeWindowProperty(native_window_property_, NULL);
+    target_widget_->SetNativeWindowProperty(native_window_property_, nullptr);
   }
 
   // WidgetObserver overrides
   void OnWidgetClosing(views::Widget* widget) override { delete this; }
 
   // WebContentsModalDialogHostObserver overrides
   void OnPositionRequiresUpdate() override {
     UpdateWidgetModalDialogPosition(target_widget_, host_);
   }
 
   void OnHostDestroying() override {
     host_->RemoveObserver(this);
-    host_ = NULL;
+    host_ = nullptr;
   }
 
  private:
   ModalDialogHost* host_;
   views::Widget* target_widget_;
   const char* const native_window_property_;
 
   DISALLOW_COPY_AND_ASSIGN(WidgetModalDialogHostObserverViews);
 };
 
@@ skipping 110 matching lines @@
       web_modal::WebContentsModalDialogManager::FromWebContents(web_contents)
           ->delegate()
           ->GetWebContentsModalDialogHost()
           ->GetHostView());
 }
 
 views::Widget* CreateBrowserModalDialogViews(views::DialogDelegate* dialog,
                                              gfx::NativeWindow parent) {
   DCHECK_NE(ui::MODAL_TYPE_CHILD, dialog->GetModalType());
   DCHECK_NE(ui::MODAL_TYPE_NONE, dialog->GetModalType());
+  DCHECK(!parent || constrained_window_views_client);
 
-  DCHECK(constrained_window_views_client);
   gfx::NativeView parent_view =
       parent ? constrained_window_views_client->GetDialogHostView(parent)
              : nullptr;
   views::Widget* widget =
-      views::DialogDelegate::CreateDialogWidget(dialog, NULL, parent_view);
+      views::DialogDelegate::CreateDialogWidget(dialog, nullptr, parent_view);
 
   bool requires_positioning = dialog->ShouldUseCustomFrame();
 
 #if defined(OS_MACOSX)
   // On Mac, window modal dialogs are displayed as sheets, so their position is
   // managed by the parent window.
   requires_positioning = false;
 #endif
 
   if (!requires_positioning)
     return widget;
 
-  ModalDialogHost* host = constrained_window_views_client->
-      GetModalDialogHost(parent);
+  ModalDialogHost* host =
+      parent ? constrained_window_views_client->GetModalDialogHost(parent)
+             : nullptr;
   if (host) {
     DCHECK_EQ(parent_view, host->GetHostView());
     ModalDialogHostObserver* dialog_host_observer =
         new WidgetModalDialogHostObserverViews(
             host, widget, kWidgetModalDialogHostObserverViewsKey);
     dialog_host_observer->OnPositionRequiresUpdate();
   }
   return widget;
 }
 
 }  // namespace constrained window