Overview Tray Button should not be visible on login screen

ash/wm/overview/window_selector_controller.cc

 // Copyright 2013 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 "ash/wm/overview/window_selector_controller.h"
 
 #include "ash/metrics/user_metrics_recorder.h"
 #include "ash/root_window_controller.h"
 #include "ash/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/overview/window_selector.h"
 #include "ash/wm/window_state.h"
 #include "ash/wm/window_util.h"
 #include "base/metrics/histogram.h"
 #include "ui/aura/window.h"
 
 namespace ash {
 
 WindowSelectorController::WindowSelectorController() {
 }
 
 WindowSelectorController::~WindowSelectorController() {
 }
 
 // static
 bool WindowSelectorController::CanSelect() {
   // Don't allow a window overview if the screen is locked or a modal dialog is
   // open.
-  return !Shell::GetInstance()->session_state_delegate()->IsScreenLocked() &&
+  return Shell::GetInstance()->session_state_delegate()->
+             IsActiveUserSessionStarted() &&

[flackr, 2014/03/28 16:56:40]

Does this work in guest mode too?

[jonross, 2014/03/28 19:39:01]

Yes it does. Verified on device.

+         !Shell::GetInstance()->session_state_delegate()->IsScreenLocked() &&
          !Shell::GetInstance()->IsSystemModalWindowOpen();
 }
 
 void WindowSelectorController::ToggleOverview() {
   if (IsSelecting()) {
     OnSelectionCanceled();
   } else {
     std::vector<aura::Window*> windows = ash::Shell::GetInstance()->
         mru_window_tracker()->BuildMruWindowList();
     // Don't enter overview mode with no windows.
@@ skipping 47 matching lines @@
   Shell* shell = Shell::GetInstance();
   shell->metrics()->RecordUserMetricsAction(UMA_WINDOW_SELECTION);
   if (!last_selection_time_.is_null()) {
     UMA_HISTOGRAM_LONG_TIMES(
         "Ash.WindowSelector.TimeBetweenUse",
         base::Time::Now() - last_selection_time_);
   }
 }
 
 }  // namespace ash