Fixes regression (and crash) in instant. The crash would happen if

views/focus/focus_manager.h

 // Copyright (c) 2011 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 VIEWS_FOCUS_FOCUS_MANAGER_H_
 #define VIEWS_FOCUS_FOCUS_MANAGER_H_
 #pragma once
 
 #include <list>
 #include <map>
@@ skipping 207 matching lines @@
   void ValidateFocusedView();
 
   // Stores and restores the focused view. Used when the window becomes
   // active/inactive.
   void StoreFocusedView();
   void RestoreFocusedView();
 
   // Clears the stored focused view.
   void ClearStoredFocusedView();
 
+  // Returns true if in the process of changing the focused view.
+  bool is_changing_focus() const { return is_changing_focus_; }
+
   // Register a keyboard accelerator for the specified target. If multiple
   // targets are registered for an accelerator, a target registered later has
   // higher priority.
   // Note that we are currently limited to accelerators that are either:
   // - a key combination including Ctrl or Alt
   // - the escape key
   // - the enter key
   // - any F key (F1, F2, F3 ...)
   // - any browser specific keys (as available on special keyboards)
   void RegisterAccelerator(const Accelerator& accelerator,
@@ skipping 68 matching lines @@
   FocusChangeReason focus_change_reason_;
 
   // The accelerators and associated targets.
   typedef std::list<AcceleratorTarget*> AcceleratorTargetList;
   typedef std::map<Accelerator, AcceleratorTargetList> AcceleratorMap;
   AcceleratorMap accelerators_;
 
   // The list of registered FocusChange listeners.
   ObserverList<FocusChangeListener, true> focus_change_listeners_;
 
+  // See description above getter.
+  bool is_changing_focus_;
+
   DISALLOW_COPY_AND_ASSIGN(FocusManager);
 };
 
 // A basic helper class that is used to disable native focus change
 // notifications within a scope.
 class AutoNativeNotificationDisabler {
  public:
   AutoNativeNotificationDisabler() {
     FocusManager::GetWidgetFocusManager()->DisableNotifications();
   }
 
   ~AutoNativeNotificationDisabler() {
     FocusManager::GetWidgetFocusManager()->EnableNotifications();
   }
  private:
   DISALLOW_COPY_AND_ASSIGN(AutoNativeNotificationDisabler);
 };
 
 }  // namespace views
 
 #endif  // VIEWS_FOCUS_FOCUS_MANAGER_H_