Revert of Potential fix for browser crash while ChromeVox is on.

chrome/browser/ui/aura/accessibility/automation_manager_aura.h

Index: chrome/browser/ui/aura/accessibility/automation_manager_aura.h
diff --git a/chrome/browser/ui/aura/accessibility/automation_manager_aura.h b/chrome/browser/ui/aura/accessibility/automation_manager_aura.h
index e7a28013bf9647feddaa8da07affcc2850c6c02a..d71be923cbef9df41945965cc3380960ce620df7 100644
--- a/chrome/browser/ui/aura/accessibility/automation_manager_aura.h
+++ b/chrome/browser/ui/aura/accessibility/automation_manager_aura.h
@@ -10,7 +10,6 @@
 #include "chrome/browser/extensions/api/automation_internal/automation_action_adapter.h"
 #include "chrome/browser/ui/aura/accessibility/ax_tree_source_aura.h"
 #include "ui/accessibility/ax_tree_serializer.h"
-#include "ui/aura/window_observer.h"
 #include "ui/views/focus/widget_focus_manager.h"
 
 template <typename T>
@@ -27,7 +26,6 @@
 
 // Manages a tree of automation nodes.
 class AutomationManagerAura : public extensions::AutomationActionAdapter,
-                              public aura::WindowObserver,
                               public views::WidgetFocusChangeListener {
  public:
   // Get the single instance of this class.
@@ -68,9 +66,6 @@
                  views::AXAuraObjWrapper* aura_obj,
                  ui::AXEvent event_type);
 
-  // aura::WindowObserver:
-  void OnWindowDestroying(aura::Window* window) override;
-
   // views::WidgetFocusChangeListener:
   void OnNativeFocusChanged(aura::Window* focused_now) override;