React to primary display change instead of removal

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

Index: chrome/browser/ui/webui/chromeos/login/oobe_display_chooser.h
diff --git a/chrome/browser/ui/webui/chromeos/login/oobe_display_chooser.h b/chrome/browser/ui/webui/chromeos/login/oobe_display_chooser.h
index 8482b9121d62d76f24112fb9f2a010244219933b..f7e2def693e0e464e336191bc8f4497381ddf30d 100644
--- a/chrome/browser/ui/webui/chromeos/login/oobe_display_chooser.h
+++ b/chrome/browser/ui/webui/chromeos/login/oobe_display_chooser.h
@@ -6,20 +6,24 @@
 #define CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_OOBE_DISPLAY_CHOOSER_H_
 
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
 
 namespace chromeos {
 
-// Tries to put the OOBE UI on a connected touch display (if available).
 class OobeDisplayChooser {
  public:
   OobeDisplayChooser();
   ~OobeDisplayChooser();
 
+  // Tries to put the OOBE UI on a connected touch display (if available).
+  // Must be called on the BrowserThread::UI thread.
   void TryToPlaceUiOnTouchDisplay();
 
  private:
   void MoveToTouchDisplay();
 
+  base::WeakPtrFactory<OobeDisplayChooser> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(OobeDisplayChooser);
 };