[protector] Support for collapsing multiple changes into a single one.

chrome/browser/protector/base_setting_change.h

 // Copyright (c) 2012 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 <utility>
 
 #include "base/basictypes.h"
 #include "base/string16.h"
 #include "chrome/browser/tabs/pinned_tab_codec.h"
 
 class Browser;
 class Profile;
 class TemplateURL;
 struct SessionStartupPref;
 
 namespace protector {
 
+class CompositeSettingsChange;
+
 // Base class for setting change tracked by Protector.
 class BaseSettingChange {
  public:
+  // Pair consisting of a display name representing either new or backup setting
+  // and priority for it. Priority is used for composite changes, consisting
+  // of multiple BaseSettingChange instances - the display name with the highest
+  // priority is used.
+  typedef std::pair<size_t, string16> DisplayName;
+
+  // Default priority value.
+  static const size_t kDefaultNamePriority;
+
   BaseSettingChange();
   virtual ~BaseSettingChange();
 
+  // Merges |this| with |other| and returns a CompositeSettingsChange instance.
+  // Returned instance takes ownership of |other|.
+  // Init should not be called for the returned instance.
+  // |this| may be another CompositeSettingsChange, in which case |other| is
+  // simply added to it and |this| is returned. |other| cannot be
+  // CompositeSettingsChange.
+  virtual CompositeSettingsChange* MergeWith(BaseSettingChange* other);
+
+  // Returns true if |this| is a result of merging some changes with |other|.
+  virtual bool Contains(const BaseSettingChange* other) const;
+
   // 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.
   // Associates this change with |profile| instance so overrides must call the
   // base method.
   virtual bool Init(Profile* profile);
 
   // Persists new setting if needed. |browser| is the Browser instance from
   // which the user action originates.
   virtual void Apply(Browser* browser);
@@ skipping 20 matching lines @@
   // 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;
 
+  // Returns the display name and priority for the new setting. If multiple
+  // BaseSettingChange instances are collapsed into MulipleSettingChange
+  // instance, the display name with the highest priority will be used for the
+  // Apply button (Discard button will have a generic caption in that case).
+  // Returns an empty string if there is no specific representaion for new

[whywhat, 2012/04/06 16:28:32]

s/representaion/representation
The function returns a pair, it can't return an empty string.

[Ivan Korotkov, 2012/04/09 14:46:47]

Done.

+  // setting value and a generic string should be used.
+  virtual DisplayName GetApplyDisplayName() const;
+
+  // Returns a keyword uniquely identifying new (to be applied) settings.
+  // BaseSettingChange instances with the same keyword may be collapsed into
+  // a single MulipleSettingChange instance. Empty keywords are not considered

[whywhat, 2012/04/06 16:28:32]

When do we have an empty keyword? When we don't know that the new setting is?

[Ivan Korotkov, 2012/04/09 14:46:47]

For settings which are not clear how to merge with others, like backup invalid
or startup changed to NTP.

+  // to be equal.
+  virtual std::string GetApplyKeyword() const;
+
  protected:
   // Profile instance we've been associated with by an |Init| call.
   Profile* profile() { return profile_; }
 
  private:
   Profile* profile_;
 
   DISALLOW_COPY_AND_ASSIGN(BaseSettingChange);
 };
 
@@ skipping 17 matching lines @@
     const SessionStartupPref& backup_startup_pref,
     const PinnedTabCodec::Tabs& backup_pinned_tabs);
 
 // Allocates and initializes BaseSettingChange implementation for an unknown
 // preferences change with invalid backup.
 BaseSettingChange* CreatePrefsBackupInvalidChange();
 
 }  // namespace protector
 
 #endif  // CHROME_BROWSER_PROTECTOR_BASE_SETTING_CHANGE_H_