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

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

Index: chrome/browser/ui/aura/accessibility/automation_manager_aura.cc
diff --git a/chrome/browser/ui/aura/accessibility/automation_manager_aura.cc b/chrome/browser/ui/aura/accessibility/automation_manager_aura.cc
index d590438569b34c7ad06eae912aac55f1775b56f6..958197370403460b7903dee4e7972ef05df60388 100644
--- a/chrome/browser/ui/aura/accessibility/automation_manager_aura.cc
+++ b/chrome/browser/ui/aura/accessibility/automation_manager_aura.cc
@@ -150,13 +150,4 @@
 
 void AutomationManagerAura::OnNativeFocusChanged(aura::Window* focused_now) {
   focused_window_ = focused_now;
-  if (focused_now && !focused_now->HasObserver(this))
-    focused_now->AddObserver(this);
 }
-
-void AutomationManagerAura::OnWindowDestroying(aura::Window* window) {
-  if (focused_window_ == window) {
-    window->RemoveObserver(this);
-    focused_window_ = nullptr;
-  }
-}