Add OnDisplayMetricsChanged in DisplayObserver.

ui/views/widget/desktop_aura/desktop_screen_x11.cc

 // Copyright (c) 2012 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/views/widget/desktop_aura/desktop_screen_x11.h"
 
 #include <X11/extensions/Xrandr.h>
 #include <X11/Xlib.h>
 
 // It clashes with out RootWindow.
@@ skipping 119 matching lines @@
       FOR_EACH_OBSERVER(gfx::DisplayObserver, observer_list_,
                         OnDisplayRemoved(*old_it));
     }
   }
 
   std::vector<gfx::Display>::const_iterator new_it = displays_.begin();
   for (; new_it != displays_.end(); ++new_it) {
     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;
+      gfx::DisplayObserver::DisplayMetrics metrics =
+          gfx::DisplayObserver::DISPLAY_METRIC_NONE;
+
+      if (new_it->bounds() != old_it->bounds())
+        metrics |= gfx::DisplayObserver::DISPLAY_METRIC_BOUNDS;
+
+      if (new_it->rotation() != old_it->rotation())
+        metrics |= gfx::DisplayObserver::DISPLAY_METRIC_ROTATION;
+
+      if (new_it->work_area() != old_it->work_area())
+        metrics |= gfx::DisplayObserver::DISPLAY_METRIC_WORK_AREA;
+
+      if (new_it->device_scale_factor() != old_it->device_scale_factor())
+        metrics |= gfx::DisplayObserver::DISPLAY_METRIC_DEVICE_SCALE_FACTOR;
+
+      if (metrics != gfx::DisplayObserver::DISPLAY_METRIC_NONE) {
+        FOR_EACH_OBSERVER(gfx::DisplayObserver,
+                          observer_list_,
+                          OnDisplayMetricsChanged(*new_it, metrics));
       }
+
+      found = true;
+      break;
     }
 
     if (!found) {
       FOR_EACH_OBSERVER(gfx::DisplayObserver, observer_list_,
                         OnDisplayAdded(*new_it));
     }
   }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ skipping 229 matching lines @@
   ProcessDisplayChange(new_displays);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 
 gfx::Screen* CreateDesktopScreen() {
   return new DesktopScreenX11;
 }
 
 }  // namespace views