Stop the OverviewButton from appearing on the Add-User screen

ash/system/overview/overview_button_tray.cc

 // Copyright 2014 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/system/overview/overview_button_tray.h"
 
+#include "ash/session/session_state_delegate.h"
 #include "ash/shelf/shelf_types.h"
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/tray_utils.h"
 #include "ash/wm/maximize_mode/maximize_mode_controller.h"
 #include "ash/wm/overview/window_selector_controller.h"
 #include "grit/ash_resources.h"
 #include "grit/ash_strings.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/resource/resource_bundle.h"
@@ skipping 18 matching lines @@
   SetContentsBackground();
 
   ui::ResourceBundle& bundle = ui::ResourceBundle::GetSharedInstance();
   icon_ = new views::ImageView();
   icon_->SetImage(
       bundle.GetImageNamed(IDR_AURA_UBER_TRAY_OVERVIEW_MODE).ToImageSkia());
   SetIconBorderForShelfAlignment();
   tray_container()->AddChildView(icon_);
 
   Shell::GetInstance()->AddShellObserver(this);
+  Shell::GetInstance()->session_state_delegate()->AddSessionStateObserver(this);
 }
 
 OverviewButtonTray::~OverviewButtonTray() {
   Shell::GetInstance()->RemoveShellObserver(this);
+  Shell::GetInstance()->session_state_delegate()->RemoveSessionStateObserver(
+      this);
 }
 
 void OverviewButtonTray::UpdateAfterLoginStatusChange(
     user::LoginStatus status) {
+  if (status == user::LOGGED_IN_KIOSK_APP) {
+    SetVisible(false);

[flackr, 2015/06/01 17:05:32]

What guarantee is there that the visibility won't be later updated not taking
into account this state? Seems like it would be better to save the loginstatus
if you can't query for LOGGED_IN_KIOSK_APP.

[jonross, 2015/06/01 17:20:37]

Good point.

Done.

+    return;
+  }
   UpdateIconVisibility();
 }
 
 bool OverviewButtonTray::PerformAction(const ui::Event& event) {
   WindowSelectorController* controller =
       Shell::GetInstance()->window_selector_controller();
   controller->ToggleOverview();
   SetDrawBackgroundAsActive(controller->IsSelecting());
   Shell::GetInstance()->metrics()->RecordUserMetricsAction(UMA_TRAY_OVERVIEW);
   return true;
 }
 
+void OverviewButtonTray::SessionStateChanged(
+    SessionStateDelegate::SessionState state) {
+  UpdateIconVisibility();
+}
+
 void OverviewButtonTray::OnMaximizeModeStarted() {
   UpdateIconVisibility();
 }
 
 void OverviewButtonTray::OnMaximizeModeEnded() {
   UpdateIconVisibility();
 }
 
 void OverviewButtonTray::OnOverviewModeEnded() {
   SetDrawBackgroundAsActive(false);
@@ skipping 33 matching lines @@
   } else {
     icon_->SetBorder(views::Border::CreateEmptyBorder(
         kVerticalShelfVerticalPadding,
         kVerticalShelfHorizontalPadding,
         kVerticalShelfVerticalPadding,
         kVerticalShelfHorizontalPadding));
   }
 }
 
 void OverviewButtonTray::UpdateIconVisibility() {
-  SetVisible(Shell::GetInstance()->maximize_mode_controller()->
-                 IsMaximizeModeWindowManagerEnabled() &&
-             Shell::GetInstance()->window_selector_controller()->CanSelect());
+  SetVisible(
+      Shell::GetInstance()
+          ->maximize_mode_controller()
+          ->IsMaximizeModeWindowManagerEnabled() &&
+      Shell::GetInstance()
+          ->session_state_delegate()
+          ->IsActiveUserSessionStarted() &&
+      !Shell::GetInstance()->session_state_delegate()->IsScreenLocked() &&
+      Shell::GetInstance()->session_state_delegate()->GetSessionState() ==
+          SessionStateDelegate::SESSION_STATE_ACTIVE);
 }
 
 }  // namespace ash