Fix crash on updating notification before attaching

ui/arc/notification/arc_notification_content_view.cc

Index: ui/arc/notification/arc_notification_content_view.cc
diff --git a/ui/arc/notification/arc_notification_content_view.cc b/ui/arc/notification/arc_notification_content_view.cc
index 312dcb97f903e63d66ce622d45743429f8169721..3f99033c95edca5245a674300edab2df34067175 100644
--- a/ui/arc/notification/arc_notification_content_view.cc
+++ b/ui/arc/notification/arc_notification_content_view.cc
@@ -360,8 +360,6 @@ void ArcNotificationContentView::SetSurface(exo::NotificationSurface* surface) {
     surface_->window()->AddObserver(this);
     surface_->window()->AddPreTargetHandler(event_forwarder_.get());
 
-    MaybeCreateFloatingControlButtons();
-
     if (GetWidget())
       AttachSurface();
   }
@@ -388,22 +386,9 @@ void ArcNotificationContentView::UpdatePreferredSize() {
 }
 
 void ArcNotificationContentView::UpdateControlButtonsVisibility() {
-  if (!surface_)
+  if (!floating_control_buttons_widget_)
     return;
 
-  // TODO(edcourtney, yhanada): Creating the floating control widget here is not
-  // correct. This function may be called during the destruction of
-  // |floating_control_buttons_widget_|. This can lead to memory corruption.
-  // Rather than creating it here, we should fix the behaviour of OnMouseExited
-  // and OnMouseEntered for ARC notifications in MessageCenterView. See
-  // crbug.com/714587 and crbug.com/709862.
-  if (!floating_control_buttons_widget_) {
-    // This may update |floating_control_buttons_widget_|.
-    MaybeCreateFloatingControlButtons();
-    if (!floating_control_buttons_widget_)
-      return;
-  }
-
   const bool target_visiblity =
       IsMouseHovered() || (close_button_ && close_button_->HasFocus()) ||
       (settings_button_ && settings_button_->HasFocus());
@@ -420,6 +405,10 @@ void ArcNotificationContentView::UpdatePinnedState() {
   if (!item_)
     return;
 
+  // Surface is not attached yet.
+  if (!control_buttons_view_)
+    return;
+
   if (item_->GetPinned() && close_button_) {
     control_buttons_view_->RemoveChildView(close_button_.get());
     close_button_.reset();
@@ -457,10 +446,8 @@ void ArcNotificationContentView::AttachSurface() {
   // 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();
+  // (Re-)create the floating buttons after |surface_| is attached to a widget.
+  MaybeCreateFloatingControlButtons();
 }
 
 void ArcNotificationContentView::StartControlButtonsColorAnimation() {