arc: Fix CreateFloatingCloseButton crash

ui/arc/notification/arc_custom_notification_view.cc

 // Copyright 2016 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/arc/notification/arc_custom_notification_view.h"
 
 #include "base/auto_reset.h"
 #include "base/memory/ptr_util.h"
 #include "components/exo/notification_surface.h"
 #include "components/exo/surface.h"
@@ skipping 240 matching lines @@
   if (ArcNotificationSurfaceManager::Get())
     ArcNotificationSurfaceManager::Get()->RemoveObserver(this);
 }
 
 std::unique_ptr<message_center::CustomNotificationContentViewDelegate>
 ArcCustomNotificationView::CreateContentViewDelegate() {
   return base::MakeUnique<ArcCustomNotificationView::ContentViewDelegate>(this);
 }
 
 void ArcCustomNotificationView::CreateFloatingCloseButton() {
-  if (!surface_)
+  // Floating close button is a transient child of |surface_| and also part
+  // of the hosting widget's focus chain. It could only be created when both
+  // are present.
+  if (!surface_ || !GetWidget())
     return;
 
   floating_close_button_ = new CloseButton(this);
 
   views::Widget::InitParams params(views::Widget::InitParams::TYPE_CONTROL);
   params.opacity = views::Widget::InitParams::TRANSLUCENT_WINDOW;
   params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
   params.parent = surface_->window();
 
   floating_close_button_widget_.reset(new views::Widget);
@@ skipping 21 matching lines @@
   }
 
   surface_ = surface;
 
   if (surface_ && surface_->window()) {
     surface_->window()->AddObserver(this);
     surface_->window()->AddPreTargetHandler(event_forwarder_.get());
 
     if (GetWidget())
       AttachSurface();
-
-    if (item_)
-      UpdatePinnedState();
   }
 }
 
 void ArcCustomNotificationView::UpdatePreferredSize() {
   gfx::Size preferred_size =
       surface_ ? surface_->GetSize() : item_ ? item_->snapshot().size()
                                              : gfx::Size();
   if (preferred_size.IsEmpty())
     return;
 
@@ skipping 48 matching lines @@
     return;
 
   UpdatePreferredSize();
   Attach(surface_->window());
 
   // Creates slide helper after this view is added to its parent.
   slide_helper_.reset(new SlideHelper(this));
 
   // Invokes Update() in case surface is attached during a slide.
   slide_helper_->Update();
+
+  // Updates pinned state to create or destroy the floating close button
+  // after |surface_| is attached to a widget.
+  if (item_)
+    UpdatePinnedState();
 }
 
 void ArcCustomNotificationView::ViewHierarchyChanged(
     const views::View::ViewHierarchyChangedDetails& details) {
   views::Widget* widget = GetWidget();
 
   if (!details.is_add) {
     // Resets slide helper when this view is removed from its parent.
     slide_helper_.reset();
 
@@ skipping 150 matching lines @@
 
 void ArcCustomNotificationView::OnNotificationSurfaceRemoved(
     exo::NotificationSurface* surface) {
   if (surface->notification_id() != notification_key_)
     return;
 
   SetSurface(nullptr);
 }
 
 }  // namespace arc