Add OnDisplayMetricsChanged in DisplayObserver.

ui/message_center/views/message_popup_collection.cc

Index: ui/message_center/views/message_popup_collection.cc
diff --git a/ui/message_center/views/message_popup_collection.cc b/ui/message_center/views/message_popup_collection.cc
index 4dd70a47128b9b0cefa16addbc37a5c531cfb362..d1116d6f3464c4807448b30f638b2d966f15dac5 100644
--- a/ui/message_center/views/message_popup_collection.cc
+++ b/ui/message_center/views/message_popup_collection.cc
@@ -561,14 +561,6 @@ void MessagePopupCollection::SetDisplayInfo(const gfx::Rect& work_area,
   RepositionWidgets();
 }
 
-void MessagePopupCollection::OnDisplayBoundsChanged(
-    const gfx::Display& display) {
-  if (display.id() != display_id_)
-    return;
-
-  SetDisplayInfo(display.work_area(), display.bounds());
-}
-
 void MessagePopupCollection::OnDisplayAdded(const gfx::Display& new_display) {
 }
 
@@ -580,6 +572,15 @@ void MessagePopupCollection::OnDisplayRemoved(const gfx::Display& old_display) {
   }
 }
 
+void MessagePopupCollection::OnDisplayMetricsChanged(
+    const gfx::Display& display, uint32_t metrics) {
+  if (display.id() != display_id_)
+    return;
+
+  if (metrics & DISPLAY_METRIC_BOUNDS || metrics & DISPLAY_METRIC_WORK_AREA)
+    SetDisplayInfo(display.work_area(), display.bounds());
+}
+
 views::Widget* MessagePopupCollection::GetWidgetForTest(const std::string& id)
     const {
   for (Toasts::const_iterator iter = toasts_.begin(); iter != toasts_.end();