chromeos: changes how DisplayManagerObservers are notified

ui/display/display_list.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/display/display_list.h"
 
 #include "base/memory/ptr_util.h"
 #include "ui/display/display_observer.h"
 
 namespace display {
@@ skipping 34 matching lines @@
     const {
   return primary_display_index_ == -1
              ? displays_.end()
              : displays_.begin() + primary_display_index_;
 }
 
 std::unique_ptr<DisplayListObserverLock> DisplayList::SuspendObserverUpdates() {
   return base::WrapUnique(new DisplayListObserverLock(this));
 }
 
+void DisplayList::AddOrUpdateDisplay(const Display& display, Type type) {
+  if (FindDisplayById(display.id()) == displays_.end())
+    AddDisplay(display, type);
+  else
+    UpdateDisplay(display, type);
+}
+
 uint32_t DisplayList::UpdateDisplay(const Display& display) {
   return UpdateDisplay(display, GetTypeByDisplayId(display.id()));
 }
 
 uint32_t DisplayList::UpdateDisplay(const Display& display, Type type) {
   auto iter = FindDisplayByIdInternal(display.id());
   DCHECK(iter != displays_.end());
 
   Display* local_display = &(*iter);
   uint32_t changed_values = 0;
@@ skipping 79 matching lines @@
 DisplayList::Displays::iterator DisplayList::FindDisplayByIdInternal(
     int64_t id) {
   for (auto iter = displays_.begin(); iter != displays_.end(); ++iter) {
     if (iter->id() == id)
       return iter;
   }
   return displays_.end();
 }
 
 }  // namespace display