Have OobeUI handle display observation

chrome/browser/ui/webui/chromeos/login/oobe_ui.h

Index: chrome/browser/ui/webui/chromeos/login/oobe_ui.h
diff --git a/chrome/browser/ui/webui/chromeos/login/oobe_ui.h b/chrome/browser/ui/webui/chromeos/login/oobe_ui.h
index 035cbbdc9bbc346dc46f5145ea48be3859f7d40a..08b06c0e8e797af9a3af48c5518176f7acfcd76d 100644
--- a/chrome/browser/ui/webui/chromeos/login/oobe_ui.h
+++ b/chrome/browser/ui/webui/chromeos/login/oobe_ui.h
@@ -19,6 +19,7 @@
 #include "chrome/browser/ui/webui/chromeos/login/base_screen_handler.h"
 #include "chrome/browser/ui/webui/chromeos/login/core_oobe_handler.h"
 #include "content/public/browser/web_ui_controller.h"
+#include "ui/display/display_observer.h"
 
 namespace ash {
 class ScreenDimmer;
@@ -68,6 +69,7 @@ class WrongHWIDScreenView;
 // - eula screen (CrOS (+ OEM) EULA content/TPM password/crash reporting).
 // - update screen.
 class OobeUI : public content::WebUIController,
+               public display::DisplayObserver,
                public ShutdownPolicyHandler::Delegate {
  public:
   // List of known types of OobeUI. Type added as path in chrome://oobe url, for
@@ -119,6 +121,12 @@ class OobeUI : public content::WebUIController,
   GaiaView* GetGaiaScreenView();
   UserBoardView* GetUserBoardView();
 
+  // Overridden from display::DisplayObserver:
+  void OnDisplayAdded(const display::Display& new_display) override;
+  void OnDisplayRemoved(const display::Display& old_display) override;
+  void OnDisplayMetricsChanged(const display::Display& display,
+                               uint32_t changed_metrics) override;
+
   // ShutdownPolicyHandler::Delegate
   void OnShutdownPolicyChanged(bool reboot_on_shutdown) override;