Enable chrome.automation.getDesktop on all aura platforms.

chrome/browser/ui/ash/accessibility/ax_root_obj_wrapper.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_ASH_ACCESSIBILITY_AX_ROOT_OBJ_WRAPPER_H_
 #define CHROME_BROWSER_UI_ASH_ACCESSIBILITY_AX_ROOT_OBJ_WRAPPER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
+#include "ui/aura/env_observer.h"
 #include "ui/views/accessibility/ax_aura_obj_wrapper.h"
 
 namespace aura {
 class Window;
 }  // namespace aura
 
-class AXRootObjWrapper : public views::AXAuraObjWrapper {
+class AXRootObjWrapper : public views::AXAuraObjWrapper,
+                         public aura::EnvObserver {
  public:
   explicit AXRootObjWrapper(int32 id);
   ~AXRootObjWrapper() override;
 
   // Returns an AXAuraObjWrapper for an alert window with title set to |text|.
   views::AXAuraObjWrapper* GetAlertForText(const std::string& text);
 
   // Convenience method to check for existence of a child.
   bool HasChild(views::AXAuraObjWrapper* child);
 
   // views::AXAuraObjWrapper overrides.
   views::AXAuraObjWrapper* GetParent() override;
   void GetChildren(
       std::vector<views::AXAuraObjWrapper*>* out_children) override;
   void Serialize(ui::AXNodeData* out_node_data) override;
   int32 GetID() override;
 
+  // aura::EnvObserver overrides.
+  void OnWindowInitialized(aura::Window* window) override;
+  void OnHostActivated(aura::WindowTreeHost* host) override;
+
  private:
   int32 id_;
 
   aura::Window* alert_window_;
 
+  aura::WindowTreeHost* host_;
+
   DISALLOW_COPY_AND_ASSIGN(AXRootObjWrapper);
 };
 
 #endif  // CHROME_BROWSER_UI_ASH_ACCESSIBILITY_AX_ROOT_OBJ_WRAPPER_H_