Add OnDisplayMetricsChanged in DisplayObserver.

ash/wm/overview/window_selector.cc

Index: ash/wm/overview/window_selector.cc
diff --git a/ash/wm/overview/window_selector.cc b/ash/wm/overview/window_selector.cc
index 3e9a478c5d7e0cd0cab5fe11417e6ab56f4923a9..04fbccb4283a9010e31878dcca72e0f254e9e2c1 100644
--- a/ash/wm/overview/window_selector.cc
+++ b/ash/wm/overview/window_selector.cc
@@ -325,16 +325,17 @@ void WindowSelector::OnTouchEvent(ui::TouchEvent* event) {
   SelectWindow(target);
 }
 
-void WindowSelector::OnDisplayBoundsChanged(const gfx::Display& display) {
-  PositionWindows(/* animate */ false);
-}
-
 void WindowSelector::OnDisplayAdded(const gfx::Display& display) {
 }
 
 void WindowSelector::OnDisplayRemoved(const gfx::Display& display) {
 }
 
+void WindowSelector::OnDisplayMetricsChanged(const gfx::Display& display,
+                                             uint32_t metrics) {
+  PositionWindows(/* animate */ false);
+}
+
 void WindowSelector::OnWindowAdded(aura::Window* new_window) {
   if (new_window->type() != ui::wm::WINDOW_TYPE_NORMAL &&
       new_window->type() != ui::wm::WINDOW_TYPE_PANEL) {