Minimal support for OOBE/login for chrome-athena

chrome/browser/chromeos/login/screens/user_selection_screen.cc

Index: chrome/browser/chromeos/login/screens/user_selection_screen.cc
diff --git a/chrome/browser/chromeos/login/screens/user_selection_screen.cc b/chrome/browser/chromeos/login/screens/user_selection_screen.cc
index be0c7821acfd10d7b47173d3abcf46aef4a953f3..c1458c2edd5dc62413ea90791f7ec09005fc8e3d 100644
--- a/chrome/browser/chromeos/login/screens/user_selection_screen.cc
+++ b/chrome/browser/chromeos/login/screens/user_selection_screen.cc
@@ -107,10 +107,12 @@ UserSelectionScreen::UserSelectionScreen() : handler_(NULL) {
 }
 
 UserSelectionScreen::~UserSelectionScreen() {
-  wm::UserActivityDetector* activity_detector =
-      ash::Shell::GetInstance()->user_activity_detector();
-  if (activity_detector->HasObserver(this))
-    activity_detector->RemoveObserver(this);
+  if (ash::Shell::HasInstance()) {
+    wm::UserActivityDetector* activity_detector =
+        ash::Shell::GetInstance()->user_activity_detector();
+    if (activity_detector->HasObserver(this))
+      activity_detector->RemoveObserver(this);
+  }
 }
 
 // static
@@ -208,10 +210,12 @@ void UserSelectionScreen::Init(const user_manager::UserList& users,
   users_ = users;
   show_guest_ = show_guest;
 
-  wm::UserActivityDetector* activity_detector =
-      ash::Shell::GetInstance()->user_activity_detector();
-  if (!activity_detector->HasObserver(this))
-    activity_detector->AddObserver(this);
+  if (ash::Shell::HasInstance()) {
+    wm::UserActivityDetector* activity_detector =
+        ash::Shell::GetInstance()->user_activity_detector();
+    if (!activity_detector->HasObserver(this))
+      activity_detector->AddObserver(this);
+  }
 }
 
 void UserSelectionScreen::OnBeforeUserRemoved(const std::string& username) {