Focus launcher if spoken feedback is enabled and no other windows visible.

ash/wm/ash_activation_controller.cc

 // Copyright (c) 2012 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/ash_activation_controller.h"
 
+#include "ash/launcher/launcher.h"
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
+#include "ash/shell_delegate.h"
 #include "ash/wm/activation_controller.h"
 #include "ash/wm/property_util.h"
 #include "ash/wm/window_util.h"
 #include "ash/wm/workspace_controller.h"
 #include "ui/views/corewm/window_modality_controller.h"
+#include "ui/views/widget/widget.h"
 
 namespace ash {
 namespace internal {
 
 ////////////////////////////////////////////////////////////////////////////////
 // AshActivationController, public:
 
 AshActivationController::AshActivationController() {
 }
 
 AshActivationController::~AshActivationController() {
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // AshActivationController, ActivationControllerDelegate implementation:
 
 aura::Window* AshActivationController::WillActivateWindow(
     aura::Window* window) {
   aura::Window* window_modal_transient =
       views::corewm::GetModalTransient(window);
   if (window_modal_transient)
     return window_modal_transient;
 
+  // Fallback to launcher
+  if (!window)
+    window = PrepareToActivateLauncher();
+
   // Make sure the workspace manager switches to the workspace for window.
   // Without this CanReceiveEvents() below returns false and activation never
   // changes. CanReceiveEvents() returns false if |window| isn't in the active
   // workspace, in which case its parent is not visible.
   // TODO(sky): if I instead change the opacity of the parent this isn't an
   // issue, but will make animations trickier... Consider which one is better.
   if (window) {
     internal::RootWindowController* root_window_controller =
         GetRootWindowController(window->GetRootWindow());
     root_window_controller->workspace_controller()->
@@ skipping 23 matching lines @@
 
 aura::Window* AshActivationController::WillFocusWindow(
     aura::Window* window) {
   aura::Window* window_modal_transient =
       views::corewm::GetModalTransient(window);
   if (window_modal_transient)
     return window_modal_transient;
   return window;
 }
 
+aura::Window* AshActivationController::PrepareToActivateLauncher() {
+  // If workspace controller is not available, then it means that the root
+  // window is being destroyed. We can't activate any window then.
+  if (!GetRootWindowController(
+      Shell::GetActiveRootWindow())->workspace_controller()) {
+    return NULL;
+  }
+  // Fallback to a launcher only when Spoken feedback is enabled.
+  if (!Shell::GetInstance()->delegate()->IsSpokenFeedbackEnabled())
+    return NULL;
+  Launcher* launcher;
+  if (Shell::IsLauncherPerDisplayEnabled()) {
+    launcher = GetRootWindowController(
+        Shell::GetActiveRootWindow())->launcher();
+  } else {
+    launcher = Launcher::ForPrimaryDisplay();
+  }
+  // Launcher is not always available, eg. not in the login screen.
+  if (!launcher)
+    return NULL;
+  views::Widget* launcher_widget = launcher->widget();
+  // Launcher's window may be already destroyed in shutting down process.
+  if (!launcher_widget)
+    return NULL;
+  aura::Window* launcher_window = launcher_widget->GetNativeWindow();
+  // Notify launcher to allow activation via CanActivate().
+  launcher->WillActivateAsFallback();
+  return launcher_window;
+}
+
 }  // namespace internal
 }  // namespace ash