Protector bubble cancels itself if user changes default search engine manually.

chrome/browser/protector/base_setting_change.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 CHROME_BROWSER_PROTECTOR_BASE_SETTING_CHANGE_H_
 #define CHROME_BROWSER_PROTECTOR_BASE_SETTING_CHANGE_H_
 #pragma once
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/string16.h"
 
 class TemplateURL;
 
 namespace protector {
 
 class Protector;
 
 // Base class for setting change tracked by Protector.
 class BaseSettingChange {
  public:
   BaseSettingChange();
   virtual ~BaseSettingChange();
 
   // Applies initial actions to the setting if needed. Must be called before
-  // any other calls are made, including text getters. Returns true if
-  // initialization was successful.
+  // any other calls are made, including text getters.
+  // Returns true if initialization was successful. Otherwise, no other
+  // calls should be made.
+  // Associates this change with |protector_| instance so overrides must
+  // call the base method.
   virtual bool Init(Protector* protector);
 
   // Persists new setting if needed.
-  virtual void Apply(Protector* protector);
+  virtual void Apply();
 
   // Restores old setting if needed.
-  virtual void Discard(Protector* protector);
+  virtual void Discard();
+
+  // Called before the change is removed from the protector instance.
+  virtual void OnBeforeRemoved() = 0;
 
   // Returns the wrench menu item and bubble title.
   virtual string16 GetBubbleTitle() const = 0;
 
   // Returns the bubble message text.
   virtual string16 GetBubbleMessage() const = 0;
 
   // Returns text for the button to apply the change with |Apply|.
   // Returns empty string if no apply button should be shown.
   virtual string16 GetApplyButtonText() const = 0;
 
   // Returns text for the button to discard the change with |Discard|.
   virtual string16 GetDiscardButtonText() const = 0;
 
+  // Protector instance we've been associated with by an |Init| call.
+  Protector* protector() { return protector_; }
+
  private:
+  Protector* protector_;
+
   DISALLOW_COPY_AND_ASSIGN(BaseSettingChange);
 };
 
 // TODO(ivankr): CompositeSettingChange that incapsulates multiple
 // BaseSettingChange instances.
 
 // Allocates and initializes SettingChange implementation for default search
 // provider setting. Both |actual| and |backup| may be NULL if corresponding
 // values are unknown or invalid.
 BaseSettingChange* CreateDefaultSearchProviderChange(
     const TemplateURL* actual,
     const TemplateURL* backup);
 
 }  // namespace protector
 
 #endif  // CHROME_BROWSER_PROTECTOR_BASE_SETTING_CHANGE_H_