Add OnDisplayMetricsChanged in DisplayObserver.

ui/views/widget/desktop_aura/desktop_screen_x11.cc

Index: ui/views/widget/desktop_aura/desktop_screen_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_screen_x11.cc b/ui/views/widget/desktop_aura/desktop_screen_x11.cc
index d9277807d443470b824144ab0ff48af2ccfcadfe..5fb28dda871a1f6ac2a391f1e9fe068eed9731eb 100644
--- a/ui/views/widget/desktop_aura/desktop_screen_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_screen_x11.cc
@@ -137,15 +137,28 @@ void DesktopScreenX11::ProcessDisplayChange(
     bool found = false;
     for (std::vector<gfx::Display>::const_iterator old_it =
          old_displays.begin(); old_it != old_displays.end(); ++old_it) {
-      if (new_it->id() == old_it->id()) {
-        if (new_it->bounds() != old_it->bounds()) {
-          FOR_EACH_OBSERVER(gfx::DisplayObserver, observer_list_,
-                            OnDisplayBoundsChanged(*new_it));
-        }
+      if (new_it->id() != old_it->id())
+        continue;
 
-        found = true;
-        break;
+      int metrics = gfx::DisplayObserver::DISPLAY_METRICS_NONE;
+
+      if (new_it->bounds() != old_it->bounds())
+        metrics |= gfx::DisplayObserver::DISPLAY_METRICS_BOUNDS;
+
+      if (new_it->rotation() != old_it->rotation())
+        metrics |= gfx::DisplayObserver::DISPLAY_METRICS_ROTATION;
+
+      if (new_it->work_area() != old_it->work_area())
+        metrics |= gfx::DisplayObserver::DISPLAY_METRICS_WORKAREA;
+
+      if (metrics != gfx::DisplayObserver::DISPLAY_METRICS_NONE) {
+        FOR_EACH_OBSERVER(gfx::DisplayObserver, observer_list_,
+            OnDisplayMetricsChanged(*new_it,
+                static_cast<gfx::DisplayObserver::MetricsType>(metrics)));
       }
+
+      found = true;
+      break;
     }
 
     if (!found) {