Prevent crash on clear-all button in message center

ui/message_center/views/message_list_view.cc

Index: ui/message_center/views/message_list_view.cc
diff --git a/ui/message_center/views/message_list_view.cc b/ui/message_center/views/message_list_view.cc
index 164dd00ec3b049a26e36b7d08626d9fa010cc72d..4b41ae3801fd27817de6c87a6e489446ce3e9a1b 100644
--- a/ui/message_center/views/message_list_view.cc
+++ b/ui/message_center/views/message_list_view.cc
@@ -302,21 +302,35 @@ void MessageListView::OnBoundsAnimatorProgressed(
 }
 
 void MessageListView::OnBoundsAnimatorDone(views::BoundsAnimator* animator) {
-  for (auto* view : deleted_when_done_)
-    delete view;
-  deleted_when_done_.clear();
+  bool need_update = false;
 
   if (clear_all_started_) {
-    clear_all_started_ = false;
+    // TODO(yoshiki): we shouldn't touch views in OnAllNotificationsCleared().
+    // Or rename it to like OnAllNotificationsClearing().
     for (auto& observer : observers_)
       observer.OnAllNotificationsCleared();
+    clear_all_started_ = false;

[Eliot Courtney, 2017/06/01 03:40:03]

What effect does moving clear_all_started_ to after the observer calls have?

[yoshiki, 2017/06/01 05:07:58]

This change was used in previous CLs but now it isn't. Reverted.

+
+    if (!deleted_when_done_.empty())
+      need_update = true;
   }
 
+  // Ensures that the views are not destroyed yet.
+  DCHECK(std::all_of(deleted_when_done_.begin(), deleted_when_done_.end(),
+                     [this](views::View* view) { return Contains(view); }));
+
+  for (auto* view : deleted_when_done_)
+    delete view;
+  deleted_when_done_.clear();
+
   if (has_deferred_task_) {
     has_deferred_task_ = false;
-    DoUpdateIfPossible();
+    need_update = true;
   }
 
+  if (need_update)
+    DoUpdateIfPossible();
+
   if (GetWidget())
     GetWidget()->SynthesizeMouseMoveEvent();