Handle modified displays in mustash.

ui/display/display_list.cc

Index: ui/display/display_list.cc
diff --git a/ui/display/display_list.cc b/ui/display/display_list.cc
index 6aea752c1442e394374357f64843b4373f874e6a..ea78b1308f9b34815bf0316dcb6d59edd2515d4e 100644
--- a/ui/display/display_list.cc
+++ b/ui/display/display_list.cc
@@ -60,6 +60,10 @@ std::unique_ptr<DisplayListObserverLock> DisplayList::SuspendObserverUpdates() {
   return base::WrapUnique(new DisplayListObserverLock(this));
 }
 
+void DisplayList::UpdateDisplay(const display::Display& display) {
+  UpdateDisplay(display, GetTypeByDisplayId(display.id()));
+}
+
 void DisplayList::UpdateDisplay(const display::Display& display, Type type) {
   auto iter = FindDisplayById(display.id());
   DCHECK(iter != displays_.end());
@@ -137,4 +141,12 @@ void DisplayList::DecrementObserverSuspendLockCount() {
   observer_suspend_lock_count_--;
 }
 
+DisplayList::Type DisplayList::GetTypeByDisplayId(int64_t display_id) const {
+  if (primary_display_index_ == -1)
+    return Type::NOT_PRIMARY;
+  return (displays_[primary_display_index_].id() == display_id
+              ? Type::PRIMARY
+              : Type::NOT_PRIMARY);
+}
+
 }  // namespace display