Add OnDisplayMetricsChanged in DisplayObserver.

ash/touch/touch_observer_hud.cc

Index: ash/touch/touch_observer_hud.cc
diff --git a/ash/touch/touch_observer_hud.cc b/ash/touch/touch_observer_hud.cc
index 60924a517b4d7298796c3aca8c2c48344ca5bf10..a870634228e41a68f0691ff3e601f2ad1c8f4329 100644
--- a/ash/touch/touch_observer_hud.cc
+++ b/ash/touch/touch_observer_hud.cc
@@ -86,12 +86,6 @@ void TouchObserverHUD::OnWidgetDestroying(views::Widget* widget) {
   delete this;
 }
 
-void TouchObserverHUD::OnDisplayBoundsChanged(const gfx::Display& display) {
-  if (display.id() != display_id_)
-    return;
-  widget_->SetSize(display.size());
-}
-
 void TouchObserverHUD::OnDisplayAdded(const gfx::Display& new_display) {}
 
 void TouchObserverHUD::OnDisplayRemoved(const gfx::Display& old_display) {
@@ -100,6 +94,14 @@ void TouchObserverHUD::OnDisplayRemoved(const gfx::Display& old_display) {
   widget_->CloseNow();
 }
 
+void TouchObserverHUD::OnDisplayMetricsChanged(
+    const gfx::Display& display, DisplayObserver::MetricsType metrics) {
+  if (display.id() != display_id_ || !(metrics & DISPLAY_METRICS_BOUNDS))
+    return;
+
+  widget_->SetSize(display.size());
+}
+
 #if defined(OS_CHROMEOS)
 void TouchObserverHUD::OnDisplayModeChanged(
     const ui::DisplayConfigurator::DisplayStateList& outputs) {