Introduce window container to be used by lock screen app windows

ash/wm/lock_action_handler_layout_manager.cc

Index: ash/wm/lock_action_handler_layout_manager.cc
diff --git a/ash/wm/lock_action_handler_layout_manager.cc b/ash/wm/lock_action_handler_layout_manager.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ebc488fc331f5c380e67263390ced0b4cdbfa793
--- /dev/null
+++ b/ash/wm/lock_action_handler_layout_manager.cc
@@ -0,0 +1,100 @@
+// Copyright 2017 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/lock_action_handler_layout_manager.h"
+
+#include <vector>
+
+#include "ash/public/cpp/shell_window_ids.h"
+#include "ash/public/interfaces/tray_action.mojom.h"
+#include "ash/shelf/shelf.h"
+#include "ash/shell.h"
+#include "ash/tray_action/tray_action.h"
+#include "ash/wm/lock_window_state.h"
+#include "ash/wm/window_state.h"
+#include "ash/wm/window_util.h"
+#include "ash/wm/wm_event.h"
+#include "ash/wm_window.h"
+
+namespace ash {
+
+LockActionHandlerLayoutManager::LockActionHandlerLayoutManager(
+    aura::Window* window,
+    Shelf* shelf)
+    : LockLayoutManager(window),
+      shelf_observer_(this),
+      tray_action_observer_(this) {
+  TrayAction* tray_action = Shell::Get()->tray_action();
+  tray_action_observer_.Add(tray_action);
+  shelf_observer_.Add(shelf);
+}
+
+LockActionHandlerLayoutManager::~LockActionHandlerLayoutManager() = default;
+
+void LockActionHandlerLayoutManager::OnWindowAddedToLayout(
+    aura::Window* child) {
+  wm::WindowState* window_state =
+      LockWindowState::SetLockWindowStateWithShelfExcluded(child);
+  wm::WMEvent event(wm::WM_EVENT_ADDED_TO_WORKSPACE);
+  window_state->OnWMEvent(&event);
+}
+
+void LockActionHandlerLayoutManager::OnChildWindowVisibilityChanged(
+    aura::Window* child,
+    bool visible) {
+  // Windows should be shown only in active state.
+  if (visible && !Shell::Get()->tray_action()->IsLockScreenNoteActive())
+    child->Hide();
+}
+
+void LockActionHandlerLayoutManager::WillChangeVisibilityState(
+    ShelfVisibilityState visibility) {
+  // Unlike LockLayoutManager, LockActionHandlerLayoutManager windows' bounds
+  // depend on the user work area bounds defined by shelf layout (see
+  // ScreenUtil::GetDisplayWorkAreaBoundsInParentForLockScreen) - when shelf
+  // bounds change, the windows in this layout manager should be updated, too.
+  const wm::WMEvent event(wm::WM_EVENT_WORKAREA_BOUNDS_CHANGED);
+  AdjustWindowsForWorkAreaChange(&event);
+}
+
+void LockActionHandlerLayoutManager::OnLockScreenNoteStateChanged(
+    mojom::TrayActionState state) {
+  // Make sure the container is properly stacked relative to lock screen
+  // container - lock action handler should be above lock screen only when a
+  // lock screen action is active.
+  if (state == mojom::TrayActionState::kActive) {
+    window()->parent()->StackChildAbove(
+        window(),
+        root_window()->GetChildById(kShellWindowId_LockScreenContainer));
+  } else {
+    window()->parent()->StackChildBelow(
+        window(),
+        root_window()->GetChildById(kShellWindowId_LockScreenContainer));
+  }
+
+  // Update children state:
+  // * a child can be visible only in background and active states
+  // * children should not be active in background state
+  // * on transition to active state:
+  //     * show hidden windows, so children that were added when action was not
+  //       in active state are shown
+  //     * activate a container child to ensure the container gets focus when
+  //       moving from background state.
+  for (aura::Window* child : window()->children()) {
+    if (state == mojom::TrayActionState::kActive) {
+      child->Show();
+    } else if (state != mojom::TrayActionState::kBackground) {
+      child->Hide();
+    } else if (wm::IsActiveWindow(child)) {
+      wm::DeactivateWindow(child);
+    }
+  }
+
+  if (!window()->children().empty() &&
+      state == mojom::TrayActionState::kActive) {
+    wm::ActivateWindow(window()->children().back());
+  }
+}
+
+}  // namespace ash