Use the DefaultSearchManager as the exclusive authority on DSE, ignoring Web Data.

chrome/browser/search_engines/default_search_pref_migration.cc

 // Copyright 2014 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.
 
 #include "chrome/browser/search_engines/default_search_pref_migration.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/search_engines/default_search_manager.h"
 #include "chrome/browser/search_engines/template_url.h"
 #include "chrome/browser/search_engines/template_url_service.h"
+#include "chrome/common/pref_names.h"
 
 namespace {
 
 // Loads the user-selected DSE (if there is one, and it's not masked by policy
 // or an extension) from legacy preferences.
 scoped_ptr<TemplateURLData> LoadDefaultSearchProviderFromPrefs(
     PrefService* pref_service) {
   scoped_ptr<TemplateURLData> legacy_dse_from_prefs;
   bool legacy_is_managed = false;
   TemplateURLService::LoadDefaultSearchProviderFromPrefs(
       pref_service, &legacy_dse_from_prefs, &legacy_is_managed);
   if (legacy_is_managed)
     legacy_dse_from_prefs.reset();
   return legacy_dse_from_prefs.Pass();
 }
 
+void ClearDefaultSearchProviderFromLegacyPrefs(PrefService* prefs) {
+  prefs->ClearPref(prefs::kDefaultSearchProviderName);
+  prefs->ClearPref(prefs::kDefaultSearchProviderKeyword);
+  prefs->ClearPref(prefs::kDefaultSearchProviderSearchURL);
+  prefs->ClearPref(prefs::kDefaultSearchProviderSuggestURL);
+  prefs->ClearPref(prefs::kDefaultSearchProviderInstantURL);
+  prefs->ClearPref(prefs::kDefaultSearchProviderImageURL);
+  prefs->ClearPref(prefs::kDefaultSearchProviderNewTabURL);
+  prefs->ClearPref(prefs::kDefaultSearchProviderSearchURLPostParams);
+  prefs->ClearPref(prefs::kDefaultSearchProviderSuggestURLPostParams);
+  prefs->ClearPref(prefs::kDefaultSearchProviderInstantURLPostParams);
+  prefs->ClearPref(prefs::kDefaultSearchProviderImageURLPostParams);
+  prefs->ClearPref(prefs::kDefaultSearchProviderIconURL);
+  prefs->ClearPref(prefs::kDefaultSearchProviderEncodings);
+  prefs->ClearPref(prefs::kDefaultSearchProviderPrepopulateID);
+  prefs->ClearPref(prefs::kDefaultSearchProviderAlternateURLs);
+  prefs->ClearPref(prefs::kDefaultSearchProviderSearchTermsReplacementKey);
+}
+
 void MigrateDefaultSearchPref(PrefService* pref_service) {
   DCHECK(pref_service);
 
   scoped_ptr<TemplateURLData> legacy_dse_from_prefs =
       LoadDefaultSearchProviderFromPrefs(pref_service);
   if (!legacy_dse_from_prefs)
     return;
 
   DefaultSearchManager default_search_manager(
       pref_service, DefaultSearchManager::ObserverCallback());
   DefaultSearchManager::Source modern_source;
   TemplateURLData* modern_value =
       default_search_manager.GetDefaultSearchEngine(&modern_source);
   if (modern_source == DefaultSearchManager::FROM_FALLBACK) {
     // |modern_value| is the prepopulated default. If it matches the legacy DSE
     // we assume it is not a user-selected value.
     if (!modern_value ||
         legacy_dse_from_prefs->prepopulate_id != modern_value->prepopulate_id) {
       // This looks like a user-selected value, so let's migrate it.
       // TODO(erikwright): Remove this migration logic when this stat approaches
       // zero.
       UMA_HISTOGRAM_BOOLEAN("Search.MigratedPrefToDictionaryValue", true);
       default_search_manager.SetUserSelectedDefaultSearchEngine(
           *legacy_dse_from_prefs);
     }
   }
 
-  // TODO(erikwright): Clear the legacy value when the modern value is the
-  // authority.
+  ClearDefaultSearchProviderFromLegacyPrefs(pref_service);
 }
 
 void OnPrefsInitialized(PrefService* pref_service,
                         bool pref_service_initialization_success) {
   MigrateDefaultSearchPref(pref_service);
 }
 
 }  // namespace
 
 void ConfigureDefaultSearchPrefMigrationToDictionaryValue(
     PrefService* pref_service) {
   if (pref_service->GetInitializationStatus() ==
       PrefService::INITIALIZATION_STATUS_WAITING) {
     pref_service->AddPrefInitObserver(
         base::Bind(&OnPrefsInitialized, base::Unretained(pref_service)));
   } else {
     MigrateDefaultSearchPref(pref_service);
   }
 }