Overview Tray Button should not be visible on login 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/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/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"
 #include "ui/views/border.h"
 #include "ui/views/controls/image_view.h"
 
 namespace {
@@ skipping 15 matching lines @@
       icon_(NULL) {
   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_);
 
-  SetVisible(Shell::GetInstance()->IsMaximizeModeWindowManagerEnabled());
+  UpdateIconVisibility(Shell::GetInstance()->
+      IsMaximizeModeWindowManagerEnabled());
 
   Shell::GetInstance()->AddShellObserver(this);
 }
 
 OverviewButtonTray::~OverviewButtonTray() {
   Shell::GetInstance()->RemoveShellObserver(this);
 }
 
+void OverviewButtonTray::UpdateAfterLoginStatusChange(
+    user::LoginStatus status) {
+  UpdateIconVisibility(Shell::GetInstance()->
+      IsMaximizeModeWindowManagerEnabled());
+}
+
 bool OverviewButtonTray::PerformAction(const ui::Event& event) {
   Shell::GetInstance()->window_selector_controller()->ToggleOverview();
   return true;
 }
 
 void OverviewButtonTray::OnMaximizeModeStarted() {
-  SetVisible(true);
+  // TODO(flackr): once maximize mode has been refactored remove this so that
+  // UpdateIconVisibility polls Shell for the status directly
+  UpdateIconVisibility(/* maximize_mode_enabled */ true);
 }
 
 void OverviewButtonTray::OnMaximizeModeEnded() {
-  SetVisible(false);
+  UpdateIconVisibility(/* maximize_mode_enabled */ false);
 }
 
 bool OverviewButtonTray::ClickedOutsideBubble() {
   // This class has no bubbles dismiss, but acknowledge that the message was
   // handled.
   return true;
 }
 
 base::string16 OverviewButtonTray::GetAccessibleNameForTray() {
   return l10n_util::GetStringUTF16(IDS_ASH_OVERVIEW_BUTTON_ACCESSIBLE_NAME);
@@ skipping 22 matching lines @@
         kHorizontalShelfHorizontalPadding));
   } else {
     icon_->SetBorder(views::Border::CreateEmptyBorder(
         kVerticalShelfVerticalPadding,
         kVerticalShelfHorizontalPadding,
         kVerticalShelfVerticalPadding,
         kVerticalShelfHorizontalPadding));
   }
 }
 
+void OverviewButtonTray::UpdateIconVisibility(bool maximize_mode_enabled) {
+  SetVisible(maximize_mode_enabled &&
+             Shell::GetInstance()->window_selector_controller()->CanSelect());
+}
+
 }  // namespace ash