Implemented 'Reset Search engines' feature.

chrome/browser/search_engines/template_url_service.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_SEARCH_ENGINES_TEMPLATE_URL_SERVICE_H_
 #define CHROME_BROWSER_SEARCH_ENGINES_TEMPLATE_URL_SERVICE_H_
 
 #include <list>
 #include <map>
 #include <set>
@@ skipping 198 matching lines @@
   // This will assert if the default search is managed; the UI should not be
   // invoking this method in that situation.
   void SetDefaultSearchProvider(TemplateURL* url);
 
   // Returns the default search provider. If the TemplateURLService hasn't been
   // loaded, the default search provider is pulled from preferences.
   //
   // NOTE: At least in unittest mode, this may return NULL.
   TemplateURL* GetDefaultSearchProvider();
 
+  // Clears user preferences describing the default search engine.
+  void ClearDefaultProviderFromPrefs();

[Peter Kasting, 2013/05/22 21:22:57]

If these two methods get called one after the other, why aren't they just one
method?

[vasilii, 2013/05/23 17:03:42]

Done.

+
+  // Clears non-extension URLs and reloads again prepopulated engines.
+  // Resets the default engine unless it's managed.

[Peter Kasting, 2013/05/22 21:22:57]

Nit: Grammar.  How about:

Resets the search providers to the prepopulated engines plus any
extension-supplied engines.  Also resets the default search engine unless it's
managed.

[vasilii, 2013/05/23 17:03:42]

Done.

+  bool ResetNonExtensionURLs();
+
   // Returns true if the default search is managed through group policy.
   bool is_default_search_managed() const { return is_default_search_managed_; }
 
   // Returns the default search specified in the prepopulated data, if it
   // exists.  If not, returns first URL in |template_urls_|, or NULL if that's
   // empty. The returned object is owned by TemplateURLService and can be
   // destroyed at any time so should be used right after the call.
   TemplateURL* FindNewDefaultSearchProvider();
 
   // Observers used to listen for changes to the model.
@@ skipping 346 matching lines @@
   // NULL if there was no pending search provider from Sync.
   TemplateURL* GetPendingSyncedDefaultSearchProvider();
 
   // Goes through a vector of TemplateURLs and ensure that both the in-memory
   // and database copies have valid sync_guids. This is to fix crbug.com/102038,
   // where old entries were being pushed to Sync without a sync_guid.
   void PatchMissingSyncGUIDs(TemplateURLVector* template_urls);
 
   void OnSyncedDefaultSearchProviderGUIDChanged();
 
+  // Adds |*template_urls| to |template_urls_| and sets up default search
+  // provider according to the internal logic.
+  // |template_urls| comes from database. The method takes ownership of
+  // |template_urls| and its elements.
+  // |default_search_provider| specifies URL inside |*template_urls|.

[Peter Kasting, 2013/05/22 21:22:57]

Nit: How about just:

Adds |template_urls| to |template_urls_| and sets up the default search
provider.  If |default_search_provider| is non-NULL, it must refer to one of the
|template_urls|, and will be used as the new default if there is no current
default.

[vasilii, 2013/05/23 17:03:42]

Done. Actually we set the default even if it's not NULL. But in both our
use-cases it's NULL.

+  void AddTemplateURLsAndSetupDefaultEngine(
+      TemplateURLVector* template_urls,
+      TemplateURL* default_search_provider);
+
+  // This sets the default search engine to FindNewDefaultSearchProvider(),
+  // if it's unmanaged and NULL.

[Peter Kasting, 2013/05/22 21:22:57]

Nit: How about:

If there is no current default search provider, sets the default to the result
of calling FindNewDefaultSearchProvider().

[vasilii, 2013/05/23 17:03:42]

Done.

+  void EnsureDefaultSearchProviderExists();
+
   content::NotificationRegistrar notification_registrar_;
   PrefChangeRegistrar pref_change_registrar_;
 
   // Mapping from keyword to the TemplateURL.
   KeywordToTemplateMap keyword_to_template_map_;
 
   // Mapping from Sync GUIDs to the TemplateURL.
   GUIDToTemplateMap guid_to_template_map_;
 
   TemplateURLVector template_urls_;
@@ skipping 75 matching lines @@
 
   // This is used to log the origin of changes to the default search provider.
   // We set this value to increasingly specific values when we know what is the
   // cause/origin of a default search change.
   DefaultSearchChangeOrigin dsp_change_origin_;
 
   DISALLOW_COPY_AND_ASSIGN(TemplateURLService);
 };
 
 #endif  // CHROME_BROWSER_SEARCH_ENGINES_TEMPLATE_URL_SERVICE_H_