Implemented 'Reset Search engines' feature.

chrome/browser/search_engines/template_url_prepopulate_data.h

Index: chrome/browser/search_engines/template_url_prepopulate_data.h
diff --git a/chrome/browser/search_engines/template_url_prepopulate_data.h b/chrome/browser/search_engines/template_url_prepopulate_data.h
index 6bd7882073ae9078d496d2be91515d0bbd43d096..3d1fa43664acc07ef7008c061c76bc2313f4ed83 100644
--- a/chrome/browser/search_engines/template_url_prepopulate_data.h
+++ b/chrome/browser/search_engines/template_url_prepopulate_data.h
@@ -54,6 +54,9 @@ void GetPrepopulatedEngines(Profile* profile,
                             std::vector<TemplateURL*>* t_urls,
                             size_t* default_search_provider_index);
 
+// Removes prepopulated engines and their version stored in user prefs.
+void ClearPrepopulatedEnginesInPrefs(Profile* profile);
+
 // Returns the default search provider specified by the prepopulate data.
 // The caller owns the returned value, which may be NULL.
 // If |profile| is NULL, any search provider overrides from the preferences are