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

ash/wm/ash_activation_controller.h

Index: ash/wm/ash_activation_controller.h
diff --git a/ash/wm/ash_activation_controller.h b/ash/wm/ash_activation_controller.h
index 0e9be46659c9d8b7bd7a36d4ddee1298fb86e080..8bc95243616a950bb307086ec828a00c8762b734 100644
--- a/ash/wm/ash_activation_controller.h
+++ b/ash/wm/ash_activation_controller.h
@@ -22,6 +22,11 @@ class AshActivationController : public ActivationControllerDelegate {
   virtual aura::Window* WillActivateWindow(aura::Window* window) OVERRIDE;
   virtual aura::Window* WillFocusWindow(aura::Window* window) OVERRIDE;
 
+  // Returns a handle to the launcher on the active root window which will
+  // be activated as fallback. Also notifies the launcher, so it can return
+  // true from Launcher::CanActivate().
+  aura::Window* PrepareToActivateLauncher();
+
   DISALLOW_COPY_AND_ASSIGN(AshActivationController);
 };