Add window overview mode behind --ash-enable-overview-mode flag to F5 key.

ash/wm/window_selector_controller.cc

Index: ash/wm/window_selector_controller.cc
diff --git a/ash/wm/window_selector_controller.cc b/ash/wm/window_selector_controller.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ff215bd2361f7366231244f5219885edd5025288
--- /dev/null
+++ b/ash/wm/window_selector_controller.cc
@@ -0,0 +1,61 @@
+// Copyright (c) 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/window_selector_controller.h"
+
+#include "ash/session_state_delegate.h"
+#include "ash/shell.h"
+#include "ash/wm/mru_window_tracker.h"
+#include "ash/wm/window_selector.h"
+#include "ash/wm/window_util.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() &&
+         !Shell::GetInstance()->IsSystemModalWindowOpen();
+}
+
+void WindowSelectorController::ToggleOverview() {
+  if (window_selector_.get()) {
+    window_selector_.reset();
+  } else {
+    std::vector<aura::Window*> windows = ash::Shell::GetInstance()->
+        mru_window_tracker()->BuildMruWindowList();
+    // Don't enter overview mode with no windows.
+    if (windows.empty())
+      return;
+
+    // Deactivating the window will hide popup windows like the omnibar or
+    // open menus.
+    aura::Window* active_window = wm::GetActiveWindow();
+    if (active_window)
+      wm::DeactivateWindow(active_window);
+    window_selector_.reset(new WindowSelector(windows, this));
+  }
+}
+
+bool WindowSelectorController::IsSelecting() {
+  return window_selector_.get() != NULL;
+}
+
+void WindowSelectorController::OnWindowSelected(aura::Window* window) {
+  window_selector_.reset();
+  wm::ActivateWindow(window);
+}
+
+void WindowSelectorController::OnSelectionCanceled() {
+  window_selector_.reset();
+}
+
+}  // namespace ash