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

chrome/browser/search_engines/template_url_service.cc

 // 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.
 
 #include "chrome/browser/search_engines/template_url_service.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 40 matching lines @@
 #include "sync/protocol/search_engine_specifics.pb.h"
 #include "sync/protocol/sync.pb.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "url/gurl.h"
 
 typedef SearchHostToURLsMap::TemplateURLSet TemplateURLSet;
 typedef TemplateURLService::SyncDataMap SyncDataMap;
 
 namespace {
 
-bool IdenticalSyncGUIDs(const TemplateURLData* data, const TemplateURL* turl) {
-  if (!data || !turl)
-    return !data && !turl;
+const char kFirstPotentialEngineHistogramName[] =
+    "Search.FirstPotentialEngineCalled";
 
-  return data->sync_guid == turl->sync_guid();
-}
+// Values for an enumerated histogram used to track whenever
+// FirstPotentialDefaultEngine is called, and from where.
+enum FirstPotentialEngineCaller {
+  FIRST_POTENTIAL_CALLSITE_FIND_NEW_DSP,
+  FIRST_POTENTIAL_CALLSITE_FIND_NEW_DSP_PROCESSING_SYNC_CHANGES,
+  FIRST_POTENTIAL_CALLSITE_ON_LOAD,
+  FIRST_POTENTIAL_CALLSITE_FIND_NEW_DSP_SYNCING,
+  FIRST_POTENTIAL_CALLSITE_FIND_NEW_DSP_NOT_SYNCING,
+  FIRST_POTENTIAL_CALLSITE_MAX,
+};
 
 const char kDeleteSyncedEngineHistogramName[] =
     "Search.DeleteSyncedSearchEngine";
 
 // Values for an enumerated histogram used to track whenever an ACTION_DELETE is
 // sent to the server for search engines.
 enum DeleteSyncedSearchEngineEvent {
   DELETE_ENGINE_USER_ACTION,
   DELETE_ENGINE_PRE_SYNC,
   DELETE_ENGINE_EMPTY_FIELD,
   DELETE_ENGINE_MAX,
 };
 
+TemplateURL* FirstPotentialDefaultEngine(
+    const TemplateURLService::TemplateURLVector& template_urls) {
+  for (TemplateURLService::TemplateURLVector::const_iterator i(
+       template_urls.begin()); i != template_urls.end(); ++i) {
+    if ((*i)->ShowInDefaultList() &&
+        ((*i)->GetType() == TemplateURL::NORMAL))
+      return *i;
+  }
+  return NULL;
+}
+
 // Returns true iff the change in |change_list| at index |i| should not be sent
 // up to the server based on its GUIDs presence in |sync_data| or when compared
 // to changes after it in |change_list|.
 // The criteria is:
 //  1) It is an ACTION_UPDATE or ACTION_DELETE and the sync_guid associated
 //     with it is NOT found in |sync_data|. We can only update and remove
 //     entries that were originally from the Sync server.
 //  2) It is an ACTION_ADD and the sync_guid associated with it is found in
 //     |sync_data|. We cannot re-add entries that Sync already knew about.
 //  3) There is an update after an update for the same GUID. We prune earlier
@@ skipping 136 matching lines @@
                   const KeywordToTemplateMap::value_type& elem2) const {
     return (elem1.second == NULL) ?
         (elem2.first.compare(0, elem1.first.length(), elem1.first) > 0) :
         (elem1.first < elem2.first);
   }
 };
 
 
 // TemplateURLService ---------------------------------------------------------
 
-// static
-bool TemplateURLService::g_fallback_search_engines_disabled = false;
-
 TemplateURLService::TemplateURLService(Profile* profile)
     : provider_map_(new SearchHostToURLsMap),
       profile_(profile),
       loaded_(false),
       load_failed_(false),
       load_handle_(0),
       default_search_provider_(NULL),
+      is_default_search_managed_(false),
       next_id_(kInvalidTemplateURLID + 1),
       time_provider_(&base::Time::Now),
       models_associated_(false),
       processing_syncer_changes_(false),
+      pending_synced_default_search_(false),
       dsp_change_origin_(DSP_CHANGE_OTHER),
       default_search_manager_(
-          GetPrefs(),
-          base::Bind(&TemplateURLService::OnDefaultSearchChange,
-                     base::Unretained(this))) {
+          GetPrefs(), DefaultSearchManager::ObserverCallback()) {
   DCHECK(profile_);
   Init(NULL, 0);
 }
 
 TemplateURLService::TemplateURLService(const Initializer* initializers,
                                        const int count)
     : provider_map_(new SearchHostToURLsMap),
       profile_(NULL),
       loaded_(false),
       load_failed_(false),
       load_handle_(0),
       service_(NULL),
       default_search_provider_(NULL),
+      is_default_search_managed_(false),
       next_id_(kInvalidTemplateURLID + 1),
       time_provider_(&base::Time::Now),
       models_associated_(false),
       processing_syncer_changes_(false),
+      pending_synced_default_search_(false),
       dsp_change_origin_(DSP_CHANGE_OTHER),
       default_search_manager_(
-          GetPrefs(),
-          base::Bind(&TemplateURLService::OnDefaultSearchChange,
-                     base::Unretained(this))) {
+          GetPrefs(), DefaultSearchManager::ObserverCallback()) {
   Init(initializers, count);
 }
 
 TemplateURLService::~TemplateURLService() {
   // |service_| should be deleted during Shutdown().
   DCHECK(!service_);
   STLDeleteElements(&template_urls_);
 }
 
 // static
@@ skipping 164 matching lines @@
   // case the term replaces the URL it's unlikely another keyword would have the
   // same url.
   // TODO(jnd): Add additional parameters to get post data when the search URL
   // has post parameters.
   return GURL(search_ref.ReplaceSearchTermsUsingTermsData(
       TemplateURLRef::SearchTermsArgs(
           base::ASCIIToUTF16("blah.blah.blah.blah.blah")),
       search_terms_data, NULL));
 }
 
-// static
 void TemplateURLService::SaveDefaultSearchProviderToPrefs(
     const TemplateURL* t_url,
-    PrefService* prefs) {
-  if (!prefs)
+    PrefService* prefs) const {
+  if (!prefs || load_failed_)
     return;
 
   bool enabled = false;
   std::string search_url;
   std::string suggest_url;
   std::string instant_url;
   std::string image_url;
   std::string new_tab_url;
   std::string search_url_post_params;
   std::string suggest_url_post_params;
@@ skipping 111 matching lines @@
       matches->push_back(i->second);
   }
 }
 
 TemplateURL* TemplateURLService::GetTemplateURLForKeyword(
     const base::string16& keyword) {
   KeywordToTemplateMap::const_iterator elem(
       keyword_to_template_map_.find(keyword));
   if (elem != keyword_to_template_map_.end())
     return elem->second;
-  return (!loaded_ &&
+  return ((!loaded_ || load_failed_) &&
       initial_default_search_provider_.get() &&
       (initial_default_search_provider_->keyword() == keyword)) ?
       initial_default_search_provider_.get() : NULL;
 }
 
 TemplateURL* TemplateURLService::GetTemplateURLForGUID(
     const std::string& sync_guid) {
   GUIDToTemplateMap::const_iterator elem(guid_to_template_map_.find(sync_guid));
   if (elem != guid_to_template_map_.end())
     return elem->second;
-  return (!loaded_ &&
+  return ((!loaded_ || load_failed_) &&
       initial_default_search_provider_.get() &&
       (initial_default_search_provider_->sync_guid() == sync_guid)) ?
       initial_default_search_provider_.get() : NULL;
 }
 
 TemplateURL* TemplateURLService::GetTemplateURLForHost(
     const std::string& host) {
   if (loaded_) {
     TemplateURL* t_url = provider_map_->GetTemplateURLForHost(host);
     if (t_url)
       return t_url;
   }
-  return (!loaded_ &&
+  return ((!loaded_ || load_failed_) &&
       initial_default_search_provider_.get() &&
       (GenerateSearchURL(initial_default_search_provider_.get()).host() ==
           host)) ? initial_default_search_provider_.get() : NULL;
 }
 
-bool TemplateURLService::Add(TemplateURL* template_url) {
+void TemplateURLService::Add(TemplateURL* template_url) {
   WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
-  if (!AddNoNotify(template_url, true))
-    return false;
-  NotifyObservers();
-  return true;
+  if (AddNoNotify(template_url, true))
+    NotifyObservers();
 }
 
 void TemplateURLService::AddAndSetProfile(TemplateURL* template_url,
                                           Profile* profile) {
   template_url->profile_ = profile;
   Add(template_url);
 }
 
 void TemplateURLService::AddWithOverrides(TemplateURL* template_url,
                                           const base::string16& short_name,
@@ skipping 16 matching lines @@
   DCHECK(info);
   DCHECK_EQ(info->wants_to_be_default_engine,
             template_url->show_in_default_list());
   template_url->extension_info_.swap(info);
   DCHECK(!FindTemplateURLForExtension(
       template_url->GetExtensionId(),
       TemplateURL::NORMAL_CONTROLLED_BY_EXTENSION));
 
   WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
   if (AddNoNotify(template_url, true)) {
-    if (template_url->extension_info_->wants_to_be_default_engine)
-      UpdateExtensionDefaultSearchEngine();
+    // Note that we can't call CanMakeDefault() here, since it would return
+    // false when another extension is already controlling the default search
+    // engine, and we want to allow new extensions to take over.
+    if (template_url->extension_info_->wants_to_be_default_engine &&
+        !is_default_search_managed()) {
+      TemplateURL* default_candidate = FindExtensionDefaultSearchEngine();
+      if (default_candidate == template_url) {
+        base::AutoReset<DefaultSearchChangeOrigin> change_origin(
+            &dsp_change_origin_, DSP_CHANGE_OVERRIDE_SETTINGS_EXTENSION);
+        SetDefaultSearchProviderNoNotify(template_url);
+      }
+    }
     NotifyObservers();
   }
 }
 
 void TemplateURLService::Remove(TemplateURL* template_url) {
   RemoveNoNotify(template_url);
   NotifyObservers();
 }
 
 void TemplateURLService::RemoveExtensionControlledTURL(
     const std::string& extension_id) {
   DCHECK(loaded_);
   TemplateURL* url = FindTemplateURLForExtension(
       extension_id, TemplateURL::NORMAL_CONTROLLED_BY_EXTENSION);
   if (!url)
     return;
-  // NULL this out so that we can call RemoveNoNotify.
-  // UpdateExtensionDefaultSearchEngine will cause it to be reset.
-  if (default_search_provider_ == url)
+  bool restore_dse = (url == GetDefaultSearchProvider());
+  if (restore_dse) {
+    DCHECK(!is_default_search_managed());
     default_search_provider_ = NULL;
+  }
   WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
   RemoveNoNotify(url);
-  UpdateExtensionDefaultSearchEngine();
+  if (restore_dse)
+    SetDefaultSearchProviderAfterRemovingDefaultExtension();
   NotifyObservers();
 }
 
 void TemplateURLService::RemoveAutoGeneratedSince(base::Time created_after) {
   RemoveAutoGeneratedBetween(created_after, base::Time());
 }
 
 void TemplateURLService::RemoveAutoGeneratedBetween(base::Time created_after,
                                                     base::Time created_before) {
   RemoveAutoGeneratedForOriginBetween(GURL(), created_after, created_before);
@@ skipping 66 matching lines @@
 
 void TemplateURLService::ResetTemplateURL(TemplateURL* url,
                                           const base::string16& title,
                                           const base::string16& keyword,
                                           const std::string& search_url) {
   if (ResetTemplateURLNoNotify(url, title, keyword, search_url))
     NotifyObservers();
 }
 
 bool TemplateURLService::CanMakeDefault(const TemplateURL* url) {
-  return
-      ((default_search_provider_source_ == DefaultSearchManager::FROM_USER) ||
-       (default_search_provider_source_ ==
-           DefaultSearchManager::FROM_FALLBACK)) &&
-       (url != GetDefaultSearchProvider()) &&
-       url->url_ref().SupportsReplacement() &&
-       (url->GetType() == TemplateURL::NORMAL);
+  return  !is_default_search_managed() &&
+      !IsExtensionControlledDefaultSearch() &&
+      (url != GetDefaultSearchProvider()) &&
+      url->url_ref().SupportsReplacement() &&
+      (url->GetType() == TemplateURL::NORMAL);
 }
 
 void TemplateURLService::SetUserSelectedDefaultSearchProvider(
     TemplateURL* url) {
-  // Omnibox keywords cannot be made default. Extension-controlled search
-  // engines can be made default only by the extension itself because they
-  // aren't persisted.
-  DCHECK(!url || (url->GetType() == TemplateURL::NORMAL));
-  if (load_failed_) {
-    // Skip the DefaultSearchManager, which will persist to user preferences.
-    if ((default_search_provider_source_ == DefaultSearchManager::FROM_USER) ||
-        (default_search_provider_source_ ==
-         DefaultSearchManager::FROM_FALLBACK)) {
-      ApplyDefaultSearchChange(url ? &url->data() : NULL,
-                               DefaultSearchManager::FROM_USER);
-    }
-  } else {
-    // We rely on the DefaultSearchManager to call OnDefaultSearchChange if, in
-    // fact, the effective DSE changes.
-    if (url)
-      default_search_manager_.SetUserSelectedDefaultSearchEngine(url->data());
-    else
-      default_search_manager_.ClearUserSelectedDefaultSearchEngine();
-  }
+  SetDefaultSearchProvider(url);
+  if (url)
+    default_search_manager_.SetUserSelectedDefaultSearchEngine(url->data());
+  else
+    default_search_manager_.ClearUserSelectedDefaultSearchEngine();
 }
 
 TemplateURL* TemplateURLService::GetDefaultSearchProvider() {
-  return loaded_ ?
-    default_search_provider_ : initial_default_search_provider_.get();
+  return (loaded_ && !load_failed_) ?
+      default_search_provider_ : initial_default_search_provider_.get();
 }
 
 bool TemplateURLService::IsSearchResultsPageFromDefaultSearchProvider(
     const GURL& url) {
   TemplateURL* default_provider = GetDefaultSearchProvider();
   return default_provider && default_provider->IsSearchURL(url);
 }
 
 bool TemplateURLService::IsExtensionControlledDefaultSearch() {
-  return default_search_provider_source_ ==
-      DefaultSearchManager::FROM_EXTENSION;
+  const TemplateURL* default_provider = GetDefaultSearchProvider();
+  return default_provider && (default_provider->GetType() ==
+      TemplateURL::NORMAL_CONTROLLED_BY_EXTENSION);
+}
+
+TemplateURL* TemplateURLService::FindNewDefaultSearchProvider() {
+  // See if the prepopulated default still exists.
+  scoped_ptr<TemplateURLData> prepopulated_default =
+      TemplateURLPrepopulateData::GetPrepopulatedDefaultSearch(GetPrefs());
+
+  for (TemplateURLVector::iterator i = template_urls_.begin();
+       i != template_urls_.end(); ++i) {
+    if ((*i)->prepopulate_id() == prepopulated_default->prepopulate_id)
+      return *i;
+  }
+  // If not, use the first non-extension keyword of the templates that supports
+  // search term replacement.
+  if (processing_syncer_changes_) {
+    UMA_HISTOGRAM_ENUMERATION(
+        kFirstPotentialEngineHistogramName,
+        FIRST_POTENTIAL_CALLSITE_FIND_NEW_DSP_PROCESSING_SYNC_CHANGES,
+        FIRST_POTENTIAL_CALLSITE_MAX);
+  } else {
+    if (sync_processor_.get()) {
+      // We're not currently in a sync cycle, but we're syncing.
+      UMA_HISTOGRAM_ENUMERATION(kFirstPotentialEngineHistogramName,
+                                FIRST_POTENTIAL_CALLSITE_FIND_NEW_DSP_SYNCING,
+                                FIRST_POTENTIAL_CALLSITE_MAX);
+    } else {
+      // We're not syncing at all.
+      UMA_HISTOGRAM_ENUMERATION(
+          kFirstPotentialEngineHistogramName,
+          FIRST_POTENTIAL_CALLSITE_FIND_NEW_DSP_NOT_SYNCING,
+          FIRST_POTENTIAL_CALLSITE_MAX);
+    }
+  }
+  return FirstPotentialDefaultEngine(template_urls_);
 }
 
 void TemplateURLService::RepairPrepopulatedSearchEngines() {
   // Can't clean DB if it hasn't been loaded.
   DCHECK(loaded());
 
-  if ((default_search_provider_source_ == DefaultSearchManager::FROM_USER) ||
-      (default_search_provider_source_ ==
-          DefaultSearchManager::FROM_FALLBACK)) {
-    // Clear |default_search_provider_| in case we want to remove the engine it
-    // points to. This will get reset at the end of the function anyway.
-    default_search_provider_ = NULL;
-  }
-
   size_t default_search_provider_index = 0;
   ScopedVector<TemplateURLData> prepopulated_urls =
       TemplateURLPrepopulateData::GetPrepopulatedEngines(
           GetPrefs(), &default_search_provider_index);
   DCHECK(!prepopulated_urls.empty());
+  int default_search_engine_id =
+      prepopulated_urls[default_search_provider_index]->prepopulate_id;
+  TemplateURL* current_dse = default_search_provider_;
   ActionsFromPrepopulateData actions(CreateActionsFromCurrentPrepopulateData(
-      &prepopulated_urls, template_urls_, default_search_provider_));
+      &prepopulated_urls, template_urls_, current_dse));
 
   WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
 
   // Remove items.
   for (std::vector<TemplateURL*>::iterator i = actions.removed_engines.begin();
        i < actions.removed_engines.end(); ++i)
     RemoveNoNotify(*i);
 
   // Edit items.
   for (EditedEngines::iterator i(actions.edited_engines.begin());
        i < actions.edited_engines.end(); ++i) {
     UIThreadSearchTermsData search_terms_data(profile());
     TemplateURL new_values(profile(), i->second);
     UpdateNoNotify(i->first, new_values, search_terms_data);
   }
 
   // Add items.
   for (std::vector<TemplateURLData>::const_iterator i =
            actions.added_engines.begin();
        i < actions.added_engines.end();
        ++i) {
     AddNoNotify(new TemplateURL(profile_, *i), true);
   }
 
-  base::AutoReset<DefaultSearchChangeOrigin> change_origin(
-      &dsp_change_origin_, DSP_CHANGE_PROFILE_RESET);
-
-  default_search_manager_.ClearUserSelectedDefaultSearchEngine();
-
-  if (!default_search_provider_) {
-    DefaultSearchManager::Source source;
-    const TemplateURLData* new_dse =
-        default_search_manager_.GetDefaultSearchEngine(&source);
-    // ApplyDefaultSearchChange will notify observers once it is done.
-    ApplyDefaultSearchChange(new_dse, source);
-  } else {
-    NotifyObservers();
+  // Change the DSE.
+  TemplateURL* new_dse = FindURLByPrepopulateID(template_urls_,
+                                                default_search_engine_id);
+  DCHECK(new_dse);
+  if (CanMakeDefault(new_dse)) {
+    base::AutoReset<DefaultSearchChangeOrigin> change_origin(
+        &dsp_change_origin_, DSP_CHANGE_PROFILE_RESET);
+    SetDefaultSearchProviderNoNotify(new_dse);
   }
+  NotifyObservers();
 }
 
 void TemplateURLService::AddObserver(TemplateURLServiceObserver* observer) {
   model_observers_.AddObserver(observer);
 }
 
 void TemplateURLService::RemoveObserver(TemplateURLServiceObserver* observer) {
   model_observers_.RemoveObserver(observer);
 }
 
 void TemplateURLService::Load() {
   if (loaded_ || load_handle_)
     return;
 
   if (!service_)
     service_ = WebDataService::FromBrowserContext(profile_);
 
-  if (service_)
+  if (service_) {
     load_handle_ = service_->GetKeywords(this);
-  else
+  } else {
     ChangeToLoadedState();
+    on_loaded_callbacks_.Notify();
+  }
 }
 
 scoped_ptr<TemplateURLService::Subscription>
     TemplateURLService::RegisterOnLoadedCallback(
         const base::Closure& callback) {
   return loaded_ ?
       scoped_ptr<TemplateURLService::Subscription>() :
       on_loaded_callbacks_.Add(callback);
 }
 
 void TemplateURLService::OnWebDataServiceRequestDone(
     WebDataService::Handle h,
     const WDTypedResult* result) {
   // Reset the load_handle so that we don't try and cancel the load in
   // the destructor.
   load_handle_ = 0;
 
   if (!result) {
     // Results are null if the database went away or (most likely) wasn't
     // loaded.
     load_failed_ = true;
     service_ = NULL;
     ChangeToLoadedState();
+    on_loaded_callbacks_.Notify();
     return;
   }
 
+  // initial_default_search_provider_ is only needed before we've finished
+  // loading. Now that we've loaded we can nuke it.
+  initial_default_search_provider_.reset();
+
   TemplateURLVector template_urls;
+  TemplateURL* default_search_provider = NULL;
   int new_resource_keyword_version = 0;
-  GetSearchProvidersUsingKeywordResult(
-      *result,
-      service_.get(),
-      profile_,
-      &template_urls,
-      (default_search_provider_source_ == DefaultSearchManager::FROM_USER) ?
-          initial_default_search_provider_.get() : NULL,
-      &new_resource_keyword_version,
+  GetSearchProvidersUsingKeywordResult(*result, service_.get(), profile_,
+      &template_urls, &default_search_provider, &new_resource_keyword_version,
       &pre_sync_deletes_);
 
   WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
 
-  PatchMissingSyncGUIDs(&template_urls);
-  SetTemplateURLs(&template_urls);
+  AddTemplateURLsAndSetupDefaultEngine(&template_urls, default_search_provider);
 
   // This initializes provider_map_ which should be done before
   // calling UpdateKeywordSearchTermsForURL.
-  // This also calls NotifyObservers.
   ChangeToLoadedState();
 
   // Index any visits that occurred before we finished loading.
   for (size_t i = 0; i < visits_to_add_.size(); ++i)
     UpdateKeywordSearchTermsForURL(visits_to_add_[i]);
   visits_to_add_.clear();
 
   if (new_resource_keyword_version)
     service_->SetBuiltinKeywordVersion(new_resource_keyword_version);
+
+  EnsureDefaultSearchProviderExists();
+
+  NotifyObservers();
+  on_loaded_callbacks_.Notify();
 }
 
 base::string16 TemplateURLService::GetKeywordShortName(
     const base::string16& keyword,
     bool* is_omnibox_api_extension_keyword) {
   const TemplateURL* template_url = GetTemplateURLForKeyword(keyword);
 
   // TODO(sky): Once LocationBarView adds a listener to the TemplateURLService
   // to track changes to the model, this should become a DCHECK.
   if (template_url) {
     *is_omnibox_api_extension_keyword =
         template_url->GetType() == TemplateURL::OMNIBOX_API_EXTENSION;
     return template_url->AdjustedShortNameForLocaleDirection();
   }
   *is_omnibox_api_extension_keyword = false;
   return base::string16();
 }
 
 void TemplateURLService::Observe(int type,
                                  const content::NotificationSource& source,
                                  const content::NotificationDetails& details) {
   if (type == chrome::NOTIFICATION_HISTORY_URL_VISITED) {
     content::Details<history::URLVisitedDetails> visit_details(details);
     if (!loaded_)
       visits_to_add_.push_back(*visit_details.ptr());
     else
       UpdateKeywordSearchTermsForURL(*visit_details.ptr());
+  } else if (type == chrome::NOTIFICATION_DEFAULT_SEARCH_POLICY_CHANGED) {
+    // Policy has been updated, so the default search prefs may be different.
+    // Reload the default search provider from them.
+    // TODO(pkasting): Rather than communicating via prefs, we should eventually
+    // observe policy changes directly.
+    UpdateDefaultSearch();
   } else {
     DCHECK_EQ(chrome::NOTIFICATION_GOOGLE_URL_UPDATED, type);
     if (loaded_) {
       GoogleBaseURLChanged(
           content::Details<GoogleURLTracker::UpdatedDetails>(details)->first);
     }
   }
 }
 
 void TemplateURLService::Shutdown() {
   // This check has to be done at Shutdown() instead of in the dtor to ensure
   // that no clients of WebDataService are holding ptrs to it after the first
   // phase of the KeyedService Shutdown() process.
   if (load_handle_) {
     DCHECK(service_.get());
     service_->CancelRequest(load_handle_);
   }
   service_ = NULL;
 }
 
+void TemplateURLService::OnSyncedDefaultSearchProviderGUIDChanged() {
+  // Listen for changes to the default search from Sync.
+  PrefService* prefs = GetPrefs();
+  TemplateURL* new_default_search = GetTemplateURLForGUID(
+      prefs->GetString(prefs::kSyncedDefaultSearchProviderGUID));
+  if (new_default_search && !is_default_search_managed_) {
+    if (new_default_search != GetDefaultSearchProvider()) {
+      base::AutoReset<DefaultSearchChangeOrigin> change_origin(
+          &dsp_change_origin_, DSP_CHANGE_SYNC_PREF);
+      SetUserSelectedDefaultSearchProvider(new_default_search);
+      pending_synced_default_search_ = false;
+    }
+  } else {
+    // If it's not there, or if default search is currently managed, set a
+    // flag to indicate that we waiting on the search engine entry to come
+    // in through Sync.
+    pending_synced_default_search_ = true;
+  }
+  UpdateDefaultSearch();
+}
+
 syncer::SyncDataList TemplateURLService::GetAllSyncData(
     syncer::ModelType type) const {
   DCHECK_EQ(syncer::SEARCH_ENGINES, type);
 
   syncer::SyncDataList current_data;
   for (TemplateURLVector::const_iterator iter = template_urls_.begin();
       iter != template_urls_.end(); ++iter) {
     // We don't sync keywords managed by policy.
     if ((*iter)->created_by_policy())
       continue;
@@ skipping 95 matching lines @@
             FROM_HERE,
             "ProcessSyncChanges failed on ChangeType ACTION_ADD");
         continue;
       }
       const std::string guid = turl->sync_guid();
       if (existing_keyword_turl) {
         // Resolve any conflicts so we can safely add the new entry.
         ResolveSyncKeywordConflict(turl.get(), existing_keyword_turl,
                                    &new_changes);
       }
-      base::AutoReset<DefaultSearchChangeOrigin> change_origin(
-          &dsp_change_origin_, DSP_CHANGE_SYNC_ADD);
       // Force the local ID to kInvalidTemplateURLID so we can add it.
       TemplateURLData data(turl->data());
       data.id = kInvalidTemplateURLID;
-      TemplateURL* added = new TemplateURL(profile_, data);
-      if (Add(added))
-        MaybeUpdateDSEAfterSync(added);
+      Add(new TemplateURL(profile_, data));
+
+      // Possibly set the newly added |turl| as the default search provider.
+      SetDefaultSearchProviderIfNewlySynced(guid);
     } else if (iter->change_type() == syncer::SyncChange::ACTION_UPDATE) {
       if (!existing_turl) {
         error = sync_error_factory_->CreateAndUploadError(
             FROM_HERE,
             "ProcessSyncChanges failed on ChangeType ACTION_UPDATE");
         continue;
       }
       if (existing_keyword_turl && (existing_keyword_turl != existing_turl)) {
         // Resolve any conflicts with other entries so we can safely update the
         // keyword.
         ResolveSyncKeywordConflict(turl.get(), existing_keyword_turl,
                                    &new_changes);
       }
       UIThreadSearchTermsData search_terms_data(existing_turl->profile());
-      if (UpdateNoNotify(existing_turl, *turl, search_terms_data)) {
+      if (UpdateNoNotify(existing_turl, *turl, search_terms_data))
         NotifyObservers();
-        MaybeUpdateDSEAfterSync(existing_turl);
-      }
     } else {
       // We've unexpectedly received an ACTION_INVALID.
       error = sync_error_factory_->CreateAndUploadError(
           FROM_HERE,
           "ProcessSyncChanges received an ACTION_INVALID");
     }
   }
 
   // If something went wrong, we want to prematurely exit to avoid pushing
   // inconsistent data to Sync. We return the last error we received.
@@ skipping 21 matching lines @@
   if (load_failed_) {
     merge_result.set_error(syncer::SyncError(
         FROM_HERE, syncer::SyncError::DATATYPE_ERROR,
         "Local database load failed.", syncer::SEARCH_ENGINES));
     return merge_result;
   }
 
   sync_processor_ = sync_processor.Pass();
   sync_error_factory_ = sync_error_factory.Pass();
 
+  // We just started syncing, so set our wait-for-default flag if we are
+  // expecting a default from Sync.
+  if (GetPrefs()) {
+    std::string default_guid = GetPrefs()->GetString(
+        prefs::kSyncedDefaultSearchProviderGUID);
+    const TemplateURL* current_default = GetDefaultSearchProvider();
+
+    if (!default_guid.empty() &&
+        (!current_default || current_default->sync_guid() != default_guid))
+      pending_synced_default_search_ = true;
+  }
+
   // We do a lot of calls to Add/Remove/ResetTemplateURL here, so ensure we
   // don't step on our own toes.
   base::AutoReset<bool> processing_changes(&processing_syncer_changes_, true);
 
   // We've started syncing, so set our origin member to the base Sync value.
   // As we move through Sync Code, we may set this to increasingly specific
   // origins so we can tell what exactly caused a DSP change.
   base::AutoReset<DefaultSearchChangeOrigin> change_origin(&dsp_change_origin_,
       DSP_CHANGE_SYNC_UNINTENTIONAL);
 
@@ skipping 58 matching lines @@
     } else {
       // The search engine from the cloud has not been synced locally. Merge it
       // into our local model. This will handle any conflicts with local (and
       // already-synced) TemplateURLs. It will prefer to keep entries from Sync
       // over not-yet-synced TemplateURLs.
       MergeInSyncTemplateURL(sync_turl.get(), sync_data_map, &new_changes,
                              &local_data_map, &merge_result);
     }
   }
 
+  // If there is a pending synced default search provider that was processed
+  // above, set it now.
+  TemplateURL* pending_default = GetPendingSyncedDefaultSearchProvider();
+  if (pending_default) {
+    base::AutoReset<DefaultSearchChangeOrigin> change_origin(
+        &dsp_change_origin_, DSP_CHANGE_SYNC_ADD);
+    SetUserSelectedDefaultSearchProvider(pending_default);
+  }
+
   // The remaining SyncData in local_data_map should be everything that needs to
   // be pushed as ADDs to sync.
   for (SyncDataMap::const_iterator iter = local_data_map.begin();
       iter != local_data_map.end(); ++iter) {
     new_changes.push_back(
         syncer::SyncChange(FROM_HERE,
                            syncer::SyncChange::ACTION_ADD,
                            iter->second));
   }
 
@@ skipping 231 matching lines @@
                                 profile_source);
     notification_registrar_.Add(this, chrome::NOTIFICATION_GOOGLE_URL_UPDATED,
                                 profile_source);
     pref_change_registrar_.Init(GetPrefs());
     pref_change_registrar_.Add(
         prefs::kSyncedDefaultSearchProviderGUID,
         base::Bind(
             &TemplateURLService::OnSyncedDefaultSearchProviderGUIDChanged,
             base::Unretained(this)));
   }
-
-  DefaultSearchManager::Source source = DefaultSearchManager::FROM_USER;
-  TemplateURLData* dse =
-      default_search_manager_.GetDefaultSearchEngine(&source);
-  ApplyDefaultSearchChange(dse, source);
+  notification_registrar_.Add(
+      this, chrome::NOTIFICATION_DEFAULT_SEARCH_POLICY_CHANGED,
+      content::NotificationService::AllSources());
 
   if (num_initializers > 0) {
     // This path is only hit by test code and is used to simulate a loaded
     // TemplateURLService.
     ChangeToLoadedState();
 
     // Add specific initializers, if any.
     WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
     for (int i(0); i < num_initializers; ++i) {
       DCHECK(initializers[i].keyword);
       DCHECK(initializers[i].url);
       DCHECK(initializers[i].content);
 
       // TemplateURLService ends up owning the TemplateURL, don't try and free
       // it.
       TemplateURLData data;
       data.short_name = base::UTF8ToUTF16(initializers[i].content);
       data.SetKeyword(base::UTF8ToUTF16(initializers[i].keyword));
       data.SetURL(initializers[i].url);
       TemplateURL* template_url = new TemplateURL(profile_, data);
       AddNoNotify(template_url, true);
 
       // Set the first provided identifier to be the default.
       if (i == 0)
-        default_search_manager_.SetUserSelectedDefaultSearchEngine(data);
+        SetDefaultSearchProviderNoNotify(template_url);
     }
   }
 
+  // Initialize default search.
+  UpdateDefaultSearch();
+
   // Request a server check for the correct Google URL if Google is the
   // default search engine and not in headless mode.
-  TemplateURL* default_search_provider = GetDefaultSearchProvider();
-  if (profile_ && default_search_provider &&
-      default_search_provider->HasGoogleBaseURLs()) {
+  if (profile_ && initial_default_search_provider_ &&
+      initial_default_search_provider_->HasGoogleBaseURLs()) {
     scoped_ptr<base::Environment> env(base::Environment::Create());
     if (!env->HasVar(env_vars::kHeadless))
       GoogleURLTracker::RequestServerCheck(profile_, false);
   }
 }
 
 void TemplateURLService::RemoveFromMaps(TemplateURL* template_url) {
   const base::string16& keyword = template_url->keyword();
   DCHECK_NE(0U, keyword_to_template_map_.count(keyword));
   if (keyword_to_template_map_[keyword] == template_url) {
@@ skipping 92 matching lines @@
   // (possibly deleted) entry.
   urls->clear();
 }
 
 void TemplateURLService::ChangeToLoadedState() {
   DCHECK(!loaded_);
 
   UIThreadSearchTermsData search_terms_data(profile_);
   provider_map_->Init(template_urls_, search_terms_data);
   loaded_ = true;
+}
 
-  // This will cause a call to NotifyObservers().
-  ApplyDefaultSearchChange(initial_default_search_provider_ ?
-                               &initial_default_search_provider_->data() : NULL,
-                           default_search_provider_source_);
-  initial_default_search_provider_.reset();
-  on_loaded_callbacks_.Notify();
+void TemplateURLService::ClearDefaultProviderFromPrefs() {
+  // We overwrite user preferences. If the default search engine is managed,
+  // there is no effect.
+  SaveDefaultSearchProviderToPrefs(NULL, GetPrefs());
+  // Default value for kDefaultSearchProviderEnabled is true.
+  PrefService* prefs = GetPrefs();
+  if (prefs)
+    prefs->SetBoolean(prefs::kDefaultSearchProviderEnabled, true);
 }
 
 bool TemplateURLService::CanReplaceKeywordForHost(
     const std::string& host,
     TemplateURL** to_replace) {
   DCHECK(!to_replace || !*to_replace);
   const TemplateURLSet* urls = provider_map_->GetURLsForHost(host);
   if (!urls)
     return true;
   for (TemplateURLSet::const_iterator i(urls->begin()); i != urls->end(); ++i) {
@@ skipping 76 matching lines @@
       }
     }
   }
   if (!existing_turl->sync_guid().empty())
     guid_to_template_map_[existing_turl->sync_guid()] = existing_turl;
 
   if (service_)
     service_->UpdateKeyword(existing_turl->data());
 
   // Inform sync of the update.
-  ProcessTemplateURLChange(
-      FROM_HERE, existing_turl, syncer::SyncChange::ACTION_UPDATE);
+  ProcessTemplateURLChange(FROM_HERE,
+                           existing_turl,
+                           syncer::SyncChange::ACTION_UPDATE);
 
-  if (default_search_provider_ == existing_turl &&
-      default_search_provider_source_ == DefaultSearchManager::FROM_USER) {
-    default_search_manager_.SetUserSelectedDefaultSearchEngine(
-        default_search_provider_->data());
+  if (default_search_provider_ == existing_turl) {
+    bool success = SetDefaultSearchProviderNoNotify(existing_turl);
+    DCHECK(success);
   }
   return true;
 }
 
 // static
 void TemplateURLService::UpdateTemplateURLIfPrepopulated(
     TemplateURL* template_url,
     Profile* profile) {
   int prepopulate_id = template_url->prepopulate_id();
   if (template_url->prepopulate_id() == 0)
     return;
 
   size_t default_search_index;
   ScopedVector<TemplateURLData> prepopulated_urls =
       TemplateURLPrepopulateData::GetPrepopulatedEngines(
           profile ? profile->GetPrefs() : NULL, &default_search_index);
 
   for (size_t i = 0; i < prepopulated_urls.size(); ++i) {
     if (prepopulated_urls[i]->prepopulate_id == prepopulate_id) {
       MergeIntoPrepopulatedEngineData(template_url, prepopulated_urls[i]);
       template_url->CopyFrom(TemplateURL(profile, *prepopulated_urls[i]));
     }
   }
 }
 
-void TemplateURLService::MaybeUpdateDSEAfterSync(TemplateURL* synced_turl) {
-  if (GetPrefs() &&
-      (synced_turl->sync_guid() ==
-          GetPrefs()->GetString(prefs::kSyncedDefaultSearchProviderGUID))) {
-    default_search_manager_.SetUserSelectedDefaultSearchEngine(
-        synced_turl->data());
-  }
-}
-
 PrefService* TemplateURLService::GetPrefs() {
   return profile_ ? profile_->GetPrefs() : NULL;
 }
 
 void TemplateURLService::UpdateKeywordSearchTermsForURL(
     const history::URLVisitedDetails& details) {
   const history::URLRow& row = details.row;
   if (!row.url().is_valid())
     return;
 
@@ skipping 77 matching lines @@
       // need to reset the keyword to an appropriate local value when this
       // change arrives; see CreateTemplateURLFromTemplateURLAndSyncData().
       UpdateNoNotify(t_url, updated_turl,
           OldBaseURLSearchTermsData(t_url->profile(), old_base_url.spec()));
     }
   }
   if (something_changed)
     NotifyObservers();
 }
 
-void TemplateURLService::OnDefaultSearchChange(
-    const TemplateURLData* data,
-    DefaultSearchManager::Source source) {
-  if (GetPrefs() && (source == DefaultSearchManager::FROM_USER) &&
-      ((source != default_search_provider_source_) ||
-       !IdenticalSyncGUIDs(data, GetDefaultSearchProvider()))) {
-    GetPrefs()->SetString(prefs::kSyncedDefaultSearchProviderGUID,
-                          data->sync_guid);
-  }
-  ApplyDefaultSearchChange(data, source);
-}
-
-void TemplateURLService::ApplyDefaultSearchChange(
-    const TemplateURLData* data,
-    DefaultSearchManager::Source source) {
+void TemplateURLService::UpdateDefaultSearch() {
   if (!loaded_) {
-    // Set |initial_default_search_provider_| from the preferences. This is
-    // mainly so we can hold ownership until we get to the point where the list
-    // of keywords from Web Data is the owner of everything including the
-    // default.
+    // Set |initial_default_search_provider_| from the preferences.  We use this
+    // value for default search provider until the database has been loaded.
+    scoped_ptr<TemplateURLData> data;
+    if (!LoadDefaultSearchProviderFromPrefs(
+            GetPrefs(), &data, &is_default_search_managed_)) {
+      // Prefs does not specify, so rely on the prepopulated engines.  This
+      // should happen only the first time Chrome is started.
+      data =
+          TemplateURLPrepopulateData::GetPrepopulatedDefaultSearch(GetPrefs());
+      is_default_search_managed_ = false;
+    }
+
     initial_default_search_provider_.reset(
         data ? new TemplateURL(profile_, *data) : NULL);
-    default_search_provider_source_ = source;
+
     return;
   }
-
-  // Prevent recursion if we update the value stored in default_search_manager_.
-  // Note that we exclude the case of data == NULL because that could cause a
-  // false positive for recursion when the initial_default_search_provider_ is
-  // NULL due to policy. We'll never actually get recursion with data == NULL.
-  if (source == default_search_provider_source_ && data != NULL &&
-      TemplateURL::MatchesData(default_search_provider_, data))
+  // Load the default search specified in prefs.
+  scoped_ptr<TemplateURLData> new_default_from_prefs;
+  bool new_is_default_managed = false;
+  // Load the default from prefs.  It's possible that it won't succeed
+  // because we are in the middle of doing SaveDefaultSearchProviderToPrefs()
+  // and all the preference items have not been saved.  In that case, we
+  // don't have yet a default.  It would be much better if we could save
+  // preferences in batches and trigger notifications at the end.
+  LoadDefaultSearchProviderFromPrefs(
+      GetPrefs(), &new_default_from_prefs, &new_is_default_managed);
+  if (!is_default_search_managed_ && !new_is_default_managed) {
+    // We're not interested in cases where the default was and remains
+    // unmanaged.  In that case, preferences have no impact on the default.
     return;
-
-  UMA_HISTOGRAM_ENUMERATION("Search.DefaultSearchChangeOrigin",
-                            dsp_change_origin_, DSP_CHANGE_MAX);
-
+  }
   WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
-  if (default_search_provider_source_ == DefaultSearchManager::FROM_POLICY ||
-      source == DefaultSearchManager::FROM_POLICY) {
-    // We do this both to remove any no-longer-applicable policy-defined DSE as
-    // well as to add the new one, if appropriate.
-    UpdateProvidersCreatedByPolicy(
-        &template_urls_,
-        source == DefaultSearchManager::FROM_POLICY ? data : NULL);
-  }
-
-  if (!data) {
-    default_search_provider_ = NULL;
-    default_search_provider_source_ = source;
-    NotifyObservers();
-    return;
-  }
-
-  if (source == DefaultSearchManager::FROM_EXTENSION) {
-    default_search_provider_ = FindMatchingExtensionTemplateURL(
-        *data, TemplateURL::NORMAL_CONTROLLED_BY_EXTENSION);
-  }
-
-  if (source == DefaultSearchManager::FROM_FALLBACK) {
-    default_search_provider_ =
-        FindPrepopulatedTemplateURL(data->prepopulate_id);
-    if (default_search_provider_) {
-      TemplateURLData update_data(*data);
-      update_data.sync_guid = default_search_provider_->sync_guid();
-      if (!default_search_provider_->safe_for_autoreplace()) {
-        update_data.safe_for_autoreplace = false;
-        update_data.SetKeyword(default_search_provider_->keyword());
-        update_data.short_name = default_search_provider_->short_name();
-      }
+  if (is_default_search_managed_ && new_is_default_managed) {
+    // The default was managed and remains managed.  Update the default only
+    // if it has changed; we don't want to respond to changes triggered by
+    // SaveDefaultSearchProviderToPrefs.
+    if (TemplateURL::MatchesData(default_search_provider_,
+                                 new_default_from_prefs.get()))
+      return;
+    if (!new_default_from_prefs) {
+      // |default_search_provider_| can't be NULL or MatchesData() would have
+      // returned true.  Remove this now invalid value.
+      TemplateURL* old_default = default_search_provider_;
+      bool success = SetDefaultSearchProviderNoNotify(NULL);
+      DCHECK(success);
+      RemoveNoNotify(old_default);
+    } else if (default_search_provider_) {
+      new_default_from_prefs->created_by_policy = true;
+      TemplateURL new_values(profile_, *new_default_from_prefs);
       UIThreadSearchTermsData search_terms_data(
           default_search_provider_->profile());
-      UpdateNoNotify(default_search_provider_,
-                     TemplateURL(profile_, update_data),
-                     search_terms_data);
+      UpdateNoNotify(default_search_provider_, new_values, search_terms_data);
     } else {
-      // Normally the prepopulated fallback should be present in
-      // |template_urls_|, but in a few cases it might not be:
-      // (1) Tests that initialize the TemplateURLService in peculiar ways.
-      // (2) If the user deleted the pre-populated default and we subsequently
-      // lost their user-selected value.
-      TemplateURL* new_dse = new TemplateURL(profile_, *data);
-      if (AddNoNotify(new_dse, true))
-        default_search_provider_ = new_dse;
-    }
-  }
-  if (source == DefaultSearchManager::FROM_USER) {
-    default_search_provider_ = GetTemplateURLForGUID(data->sync_guid);
-    if (!default_search_provider_ && data->prepopulate_id) {
-      default_search_provider_ =
-          FindPrepopulatedTemplateURL(data->prepopulate_id);
-    }
-    TemplateURLData new_data(*data);
-    new_data.show_in_default_list = true;
-    if (default_search_provider_) {
-      UIThreadSearchTermsData search_terms_data(
-          default_search_provider_->profile());
-      UpdateNoNotify(default_search_provider_,
-                     TemplateURL(profile_, new_data),
-                     search_terms_data);
+      TemplateURL* new_template = NULL;
+      if (new_default_from_prefs) {
+        new_default_from_prefs->created_by_policy = true;
+        new_template = new TemplateURL(profile_, *new_default_from_prefs);
+        if (!AddNoNotify(new_template, true))
+          return;
+      }
+      bool success = SetDefaultSearchProviderNoNotify(new_template);
+      DCHECK(success);
+    }
+  } else if (!is_default_search_managed_ && new_is_default_managed) {
+    // The default used to be unmanaged and is now managed.  Add the new
+    // managed default to the list of URLs and set it as default.
+    is_default_search_managed_ = new_is_default_managed;
+    TemplateURL* new_template = NULL;
+    if (new_default_from_prefs) {
+      new_default_from_prefs->created_by_policy = true;
+      new_template = new TemplateURL(profile_, *new_default_from_prefs);
+      if (!AddNoNotify(new_template, true))
+        return;
+    }
+    bool success = SetDefaultSearchProviderNoNotify(new_template);
+    DCHECK(success);
+  } else {
+    // The default was managed and is no longer.
+    DCHECK(is_default_search_managed_ && !new_is_default_managed);
+    is_default_search_managed_ = new_is_default_managed;
+    // If we had a default, delete the previous default if created by policy
+    // and set a likely default.
+    if ((default_search_provider_ != NULL) &&
+        default_search_provider_->created_by_policy()) {
+      TemplateURL* old_default = default_search_provider_;
+      default_search_provider_ = NULL;
+      RemoveNoNotify(old_default);
+    }
+
+    // The likely default should be from Sync if we were waiting on Sync.
+    // Otherwise, it should be FindNewDefaultSearchProvider.
+    TemplateURL* synced_default = GetPendingSyncedDefaultSearchProvider();
+    if (synced_default) {
+      pending_synced_default_search_ = false;
+
+      base::AutoReset<DefaultSearchChangeOrigin> change_origin(
+          &dsp_change_origin_, DSP_CHANGE_SYNC_NOT_MANAGED);
+      SetDefaultSearchProviderNoNotify(synced_default);
     } else {
-      new_data.id = kInvalidTemplateURLID;
-      TemplateURL* new_dse = new TemplateURL(profile_, new_data);
-      if (AddNoNotify(new_dse, true))
-        default_search_provider_ = new_dse;
-    }
-    if (default_search_provider_ && GetPrefs()) {
-      GetPrefs()->SetString(
-          prefs::kSyncedDefaultSearchProviderGUID,
-          default_search_provider_->sync_guid());
-    }
-
-  }
-
-  default_search_provider_source_ = source;
-
-  if (default_search_provider_ &&
-      default_search_provider_->HasGoogleBaseURLs()) {
-    if (profile_)
+      SetDefaultSearchProviderNoNotify(FindNewDefaultSearchProvider());
+    }
+  }
+  NotifyObservers();
+}
+
+void TemplateURLService::SetDefaultSearchProvider(
+    TemplateURL* url) {
+  DCHECK(!is_default_search_managed_);
+  // Omnibox keywords cannot be made default. Extension-controlled search
+  // engines can be made default only by the extension itself because they
+  // aren't persisted.
+  DCHECK(!url || (url->GetType() == TemplateURL::NORMAL));
+
+  // Always persist the setting in the database, that way if the backup
+  // signature has changed out from under us it gets reset correctly.
+  if (SetDefaultSearchProviderNoNotify(url))
+    NotifyObservers();
+}
+
+bool TemplateURLService::SetDefaultSearchProviderNoNotify(TemplateURL* url) {
+  if (url) {
+    if (std::find(template_urls_.begin(), template_urls_.end(), url) ==
+        template_urls_.end())
+      return false;
+    // Omnibox keywords cannot be made default.
+    DCHECK_NE(TemplateURL::OMNIBOX_API_EXTENSION, url->GetType());
+  }
+
+  // Only bother reassigning |url| if it has changed. Notice that we don't just
+  // early exit if they are equal, because |url| may have had its fields
+  // changed, and needs to be persisted below (for example, when this is called
+  // from UpdateNoNotify).
+  if (default_search_provider_ != url) {
+    // Engines set by policy override extension-controlled engines, which
+    // override other engines.
+    DCHECK(!is_default_search_managed() || !url ||
+           (url->GetType() == TemplateURL::NORMAL));
+    if (is_default_search_managed() || !default_search_provider_ ||
+        (default_search_provider_->GetType() == TemplateURL::NORMAL) ||
+        (url &&
+         (url->GetType() == TemplateURL::NORMAL_CONTROLLED_BY_EXTENSION))){
+      UMA_HISTOGRAM_ENUMERATION("Search.DefaultSearchChangeOrigin",
+                                dsp_change_origin_, DSP_CHANGE_MAX);
+      default_search_provider_ = url;
+    }
+  }
+
+  if (url) {
+    // Don't mark the url as edited, otherwise we won't be able to rev the
+    // template urls we ship with.
+    url->data_.show_in_default_list = true;
+    if (service_ && (url->GetType() == TemplateURL::NORMAL))
+      service_->UpdateKeyword(url->data());
+
+    if (url->HasGoogleBaseURLs()) {
       GoogleURLTracker::RequestServerCheck(profile_, false);
 #if defined(ENABLE_RLZ)
-    RLZTracker::RecordProductEvent(rlz_lib::CHROME,
-                                   RLZTracker::CHROME_OMNIBOX,
-                                   rlz_lib::SET_TO_GOOGLE);
+      RLZTracker::RecordProductEvent(rlz_lib::CHROME,
+                                     RLZTracker::CHROME_OMNIBOX,
+                                     rlz_lib::SET_TO_GOOGLE);
 #endif
-  }
-
-  NotifyObservers();
+    }
+  }
+
+  // Extension-controlled search engines shouldn't be persisted anywhere.
+  if (url && (url->GetType() == TemplateURL::NORMAL_CONTROLLED_BY_EXTENSION))
+    return true;
+
+  if (!is_default_search_managed_) {
+    SaveDefaultSearchProviderToPrefs(url, GetPrefs());
+
+    // If we are syncing, we want to set the synced pref that will notify other
+    // instances to change their default to this new search provider.
+    // Note: we don't update the pref if we're currently in the middle of
+    // handling a sync operation. Sync operations from other clients are not
+    // guaranteed to arrive together, and any client that deletes the default
+    // needs to set a new default as well. If we update the default here, we're
+    // likely to race with the update from the other client, resulting in
+    // a possibly random default search provider.
+    if (sync_processor_.get() && url && !url->sync_guid().empty() &&
+        GetPrefs() && !processing_syncer_changes_) {
+      GetPrefs()->SetString(prefs::kSyncedDefaultSearchProviderGUID,
+                            url->sync_guid());
+    }
+  }
+
+  if (service_)
+    service_->SetDefaultSearchProviderID(url ? url->id() : 0);
+
+  // Inform sync the change to the show_in_default_list flag.
+  if (url)
+    ProcessTemplateURLChange(FROM_HERE,
+                             url,
+                             syncer::SyncChange::ACTION_UPDATE);
+  return true;
 }
 
 bool TemplateURLService::AddNoNotify(TemplateURL* template_url,
                                      bool newly_adding) {
   DCHECK(template_url);
 
   if (newly_adding) {
     DCHECK_EQ(kInvalidTemplateURLID, template_url->id());
     DCHECK(std::find(template_urls_.begin(), template_urls_.end(),
                      template_url) == template_urls_.end());
@@ skipping 94 matching lines @@
   TemplateURLData data(url->data());
   data.short_name = title;
   data.SetKeyword(keyword);
   if (search_url != data.url()) {
     data.SetURL(search_url);
     // The urls have changed, reset the favicon url.
     data.favicon_url = GURL();
   }
   data.safe_for_autoreplace = false;
   data.last_modified = time_provider_();
+  TemplateURL new_url(url->profile(), data);
   UIThreadSearchTermsData search_terms_data(url->profile());
-  return UpdateNoNotify(url, TemplateURL(profile_, data), search_terms_data);
+  return UpdateNoNotify(url, new_url, search_terms_data);
 }
 
 void TemplateURLService::NotifyObservers() {
   if (!loaded_)
     return;
 
   FOR_EACH_OBSERVER(TemplateURLServiceObserver, model_observers_,
                     OnTemplateURLServiceChanged());
 }
 
 // |template_urls| are the TemplateURLs loaded from the database.
-// |default_from_prefs| is the default search provider from the preferences, or
-// NULL if the DSE is not policy-defined.
+// |default_search_provider| points to one of them, if it was set in the db.
+// |default_from_prefs| is the default search provider from the preferences.
+// Check |is_default_search_managed_| to determine if it was set by policy.
 //
 // This function removes from the vector and the database all the TemplateURLs
-// that were set by policy, unless it is the current default search provider, in
-// which case it is updated with the data from prefs.
-void TemplateURLService::UpdateProvidersCreatedByPolicy(
+// that were set by policy, unless it is the current default search provider
+// and matches what is set by a managed preference.
+void TemplateURLService::RemoveProvidersCreatedByPolicy(
     TemplateURLVector* template_urls,
-    const TemplateURLData* default_from_prefs) {
+    TemplateURL** default_search_provider,
+    TemplateURLData* default_from_prefs) {
   DCHECK(template_urls);
-
+  DCHECK(default_search_provider);
   for (TemplateURLVector::iterator i = template_urls->begin();
        i != template_urls->end(); ) {
     TemplateURL* template_url = *i;
     if (template_url->created_by_policy()) {
-      if (default_from_prefs &&
+      if (template_url == *default_search_provider &&
+          is_default_search_managed_ &&
           TemplateURL::MatchesData(template_url, default_from_prefs)) {
         // If the database specified a default search provider that was set
         // by policy, and the default search provider from the preferences
         // is also set by policy and they are the same, keep the entry in the
         // database and the |default_search_provider|.
-        default_search_provider_ = template_url;
-        // Prevent us from saving any other entries, or creating a new one.
-        default_from_prefs = NULL;
         ++i;
         continue;
       }
 
-      RemoveFromMaps(template_url);
+      // The database loaded a managed |default_search_provider|, but it has
+      // been updated in the prefs. Remove it from the database, and update the
+      // |default_search_provider| pointer here.
+      if (*default_search_provider &&
+          (*default_search_provider)->id() == template_url->id())
+        *default_search_provider = NULL;
+
       i = template_urls->erase(i);
       if (service_)
         service_->RemoveKeyword(template_url->id());
       delete template_url;
     } else {
       ++i;
     }
   }
-
-  if (default_from_prefs) {
-    default_search_provider_ = NULL;
-    default_search_provider_source_ = DefaultSearchManager::FROM_POLICY;
-    TemplateURLData new_data(*default_from_prefs);
-    if (new_data.sync_guid.empty())
-      new_data.sync_guid = base::GenerateGUID();
-    new_data.created_by_policy = true;
-    TemplateURL* new_dse = new TemplateURL(profile_, new_data);
-    if (AddNoNotify(new_dse, true))
-      default_search_provider_ = new_dse;
-  }
 }
 
 void TemplateURLService::ResetTemplateURLGUID(TemplateURL* url,
                                               const std::string& guid) {
   DCHECK(loaded_);
   DCHECK(!guid.empty());
 
   TemplateURLData data(url->data());
   data.sync_guid = guid;
+  TemplateURL new_url(url->profile(), data);
   UIThreadSearchTermsData search_terms_data(url->profile());
-  UpdateNoNotify(url, TemplateURL(profile_, data), search_terms_data);
+  UpdateNoNotify(url, new_url, search_terms_data);
 }
 
 base::string16 TemplateURLService::UniquifyKeyword(const TemplateURL& turl,
                                                    bool force) {
   if (!force) {
     // Already unique.
     if (!GetTemplateURLForKeyword(turl.keyword()))
       return turl.keyword();
 
     // First, try to return the generated keyword for the TemplateURL (except
@@ skipping 50 matching lines @@
   base::string16 new_keyword = UniquifyKeyword(*loser, false);
   DCHECK(!GetTemplateURLForKeyword(new_keyword));
   if (applied_turl_is_better) {
     // Just set the keyword of |unapplied_sync_turl|. The caller is responsible
     // for adding or updating unapplied_sync_turl in the local model.
     unapplied_sync_turl->data_.SetKeyword(new_keyword);
   } else {
     // Update |applied_sync_turl| in the local model with the new keyword.
     TemplateURLData data(applied_sync_turl->data());
     data.SetKeyword(new_keyword);
+    TemplateURL new_turl(applied_sync_turl->profile(), data);
     UIThreadSearchTermsData search_terms_data(applied_sync_turl->profile());
-    if (UpdateNoNotify(
-            applied_sync_turl, TemplateURL(profile_, data), search_terms_data))
+    if (UpdateNoNotify(applied_sync_turl, new_turl, search_terms_data))
       NotifyObservers();
   }
   // The losing TemplateURL should have their keyword updated. Send a change to
   // the server to reflect this change.
   syncer::SyncData sync_data = CreateSyncDataFromTemplateURL(*loser);
   change_list->push_back(syncer::SyncChange(FROM_HERE,
       syncer::SyncChange::ACTION_UPDATE,
       sync_data));
 }
 
@@ skipping 28 matching lines @@
       // |conflicting_turl| is not yet known to Sync. If it is better, then we
       // want to transfer its values up to sync. Otherwise, we remove it and
       // allow the entry from Sync to overtake it in the model.
       const std::string guid = conflicting_turl->sync_guid();
       if (IsLocalTemplateURLBetter(conflicting_turl, sync_turl)) {
         ResetTemplateURLGUID(conflicting_turl, sync_turl->sync_guid());
         syncer::SyncData sync_data =
             CreateSyncDataFromTemplateURL(*conflicting_turl);
         change_list->push_back(syncer::SyncChange(
             FROM_HERE, syncer::SyncChange::ACTION_UPDATE, sync_data));
+        if (conflicting_turl == GetDefaultSearchProvider() &&
+            !pending_synced_default_search_) {
+          // If we're not waiting for the Synced default to come in, we should
+          // override the pref with our new GUID. If we are waiting for the
+          // arrival of a synced default, setting the pref here would cause us
+          // to lose the GUID we are waiting on.
+          PrefService* prefs = GetPrefs();
+          if (prefs) {
+            prefs->SetString(prefs::kSyncedDefaultSearchProviderGUID,
+                             conflicting_turl->sync_guid());
+          }
+        }
         // Note that in this case we do not add the Sync TemplateURL to the
         // local model, since we've effectively "merged" it in by updating the
         // local conflicting entry with its sync_guid.
         should_add_sync_turl = false;
         merge_result->set_num_items_modified(
             merge_result->num_items_modified() + 1);
       } else {
         // We guarantee that this isn't the local search provider. Otherwise,
         // local would have won.
         DCHECK(conflicting_turl != GetDefaultSearchProvider());
         Remove(conflicting_turl);
         merge_result->set_num_items_deleted(
             merge_result->num_items_deleted() + 1);
       }
       // This TemplateURL was either removed or overwritten in the local model.
       // Remove the entry from the local data so it isn't pushed up to Sync.
       local_data->erase(guid);
     }
   }
 
   if (should_add_sync_turl) {
     // Force the local ID to kInvalidTemplateURLID so we can add it.
     TemplateURLData data(sync_turl->data());
     data.id = kInvalidTemplateURLID;
-    TemplateURL* added = new TemplateURL(profile_, data);
-    base::AutoReset<DefaultSearchChangeOrigin> change_origin(
-        &dsp_change_origin_, DSP_CHANGE_SYNC_ADD);
-    if (Add(added))
-      MaybeUpdateDSEAfterSync(added);
+    Add(new TemplateURL(profile_, data));
     merge_result->set_num_items_added(
         merge_result->num_items_added() + 1);
   }
 }
 
+void TemplateURLService::SetDefaultSearchProviderIfNewlySynced(
+    const std::string& guid) {
+  // If we're not syncing or if default search is managed by policy, ignore.
+  if (!sync_processor_.get() || is_default_search_managed_)
+    return;
+
+  PrefService* prefs = GetPrefs();
+  if (prefs && pending_synced_default_search_ &&
+      prefs->GetString(prefs::kSyncedDefaultSearchProviderGUID) == guid) {
+    // Make sure this actually exists. We should not be calling this unless we
+    // really just added this TemplateURL.
+    TemplateURL* turl_from_sync = GetTemplateURLForGUID(guid);
+    if (turl_from_sync && turl_from_sync->SupportsReplacement()) {
+      base::AutoReset<DefaultSearchChangeOrigin> change_origin(
+          &dsp_change_origin_, DSP_CHANGE_SYNC_ADD);
+      SetDefaultSearchProvider(turl_from_sync);
+    }
+    pending_synced_default_search_ = false;
+  }
+}
+
+TemplateURL* TemplateURLService::GetPendingSyncedDefaultSearchProvider() {
+  PrefService* prefs = GetPrefs();
+  if (!prefs || !pending_synced_default_search_)
+    return NULL;
+
+  // Could be NULL if no such thing exists.
+  return GetTemplateURLForGUID(
+      prefs->GetString(prefs::kSyncedDefaultSearchProviderGUID));
+}
+
 void TemplateURLService::PatchMissingSyncGUIDs(
     TemplateURLVector* template_urls) {
   DCHECK(template_urls);
   for (TemplateURLVector::iterator i = template_urls->begin();
        i != template_urls->end(); ++i) {
     TemplateURL* template_url = *i;
     DCHECK(template_url);
     if (template_url->sync_guid().empty() &&
         (template_url->GetType() !=
             TemplateURL::NORMAL_CONTROLLED_BY_EXTENSION)) {
       template_url->data_.sync_guid = base::GenerateGUID();
       if (service_)
         service_->UpdateKeyword(template_url->data());
     }
   }
 }
 
-void TemplateURLService::OnSyncedDefaultSearchProviderGUIDChanged() {
-  base::AutoReset<DefaultSearchChangeOrigin> change_origin(
-      &dsp_change_origin_, DSP_CHANGE_SYNC_PREF);
+void TemplateURLService::AddTemplateURLsAndSetupDefaultEngine(
+    TemplateURLVector* template_urls,
+    TemplateURL* default_search_provider) {
+  DCHECK(template_urls);
+  is_default_search_managed_ = false;
+  bool database_specified_a_default = (default_search_provider != NULL);
 
-  std::string new_guid =
-      GetPrefs()->GetString(prefs::kSyncedDefaultSearchProviderGUID);
-  if (new_guid.empty()) {
-    default_search_manager_.ClearUserSelectedDefaultSearchEngine();
-    return;
+  // Check if default search provider is now managed.
+  scoped_ptr<TemplateURLData> default_from_prefs;
+  LoadDefaultSearchProviderFromPrefs(
+      GetPrefs(), &default_from_prefs, &is_default_search_managed_);
+
+  // Remove entries that were created because of policy as they may have
+  // changed since the database was saved.
+  RemoveProvidersCreatedByPolicy(template_urls,
+                                 &default_search_provider,
+                                 default_from_prefs.get());
+
+  PatchMissingSyncGUIDs(template_urls);
+
+  if (is_default_search_managed_) {
+    SetTemplateURLs(template_urls);
+
+    if (TemplateURL::MatchesData(default_search_provider,
+                                 default_from_prefs.get())) {
+      // The value from the preferences was previously stored in the database.
+      // Reuse it.
+    } else {
+      // The value from the preferences takes over.
+      default_search_provider = NULL;
+      if (default_from_prefs) {
+        default_from_prefs->created_by_policy = true;
+        default_from_prefs->id = kInvalidTemplateURLID;
+        default_search_provider =
+            new TemplateURL(profile_, *default_from_prefs);
+        if (!AddNoNotify(default_search_provider, true))
+          default_search_provider = NULL;
+      }
+    }
+    // Note that this saves the default search provider to prefs.
+    if (!default_search_provider ||
+        ((default_search_provider->GetType() !=
+            TemplateURL::OMNIBOX_API_EXTENSION) &&
+         default_search_provider->SupportsReplacement())) {
+      bool success = SetDefaultSearchProviderNoNotify(default_search_provider);
+      DCHECK(success);
+    }
+  } else {
+    // If we had a managed default, replace it with the synced default if
+    // applicable, or the first provider of the list.
+    TemplateURL* synced_default = GetPendingSyncedDefaultSearchProvider();
+    if (synced_default) {
+      default_search_provider = synced_default;
+      pending_synced_default_search_ = false;
+    } else if (database_specified_a_default &&
+        default_search_provider == NULL) {
+      UMA_HISTOGRAM_ENUMERATION(kFirstPotentialEngineHistogramName,
+                                FIRST_POTENTIAL_CALLSITE_ON_LOAD,
+                                FIRST_POTENTIAL_CALLSITE_MAX);
+      default_search_provider = FirstPotentialDefaultEngine(*template_urls);
+    }
+
+    // If the default search provider existed previously, then just
+    // set the member variable. Otherwise, we'll set it using the method
+    // to ensure that it is saved properly after its id is set.
+    if (default_search_provider &&
+        (default_search_provider->id() != kInvalidTemplateURLID)) {
+      default_search_provider_ = default_search_provider;
+      default_search_provider = NULL;
+    }
+    SetTemplateURLs(template_urls);
+
+    if (default_search_provider) {
+      base::AutoReset<DefaultSearchChangeOrigin> change_origin(
+          &dsp_change_origin_, default_from_prefs ?
+              dsp_change_origin_ : DSP_CHANGE_NEW_ENGINE_NO_PREFS);
+      // Note that this saves the default search provider to prefs.
+      SetDefaultSearchProvider(default_search_provider);
+    } else {
+      // Always save the default search provider to prefs. That way we don't
+      // have to worry about it being out of sync.
+      if (default_search_provider_)
+        SaveDefaultSearchProviderToPrefs(default_search_provider_, GetPrefs());
+    }
   }
-
-  TemplateURL* turl = GetTemplateURLForGUID(new_guid);
-  if (turl)
-    default_search_manager_.SetUserSelectedDefaultSearchEngine(turl->data());
 }
 
-TemplateURL* TemplateURLService::FindPrepopulatedTemplateURL(
-    int prepopulated_id) {
-  for (TemplateURLVector::const_iterator i = template_urls_.begin();
-       i != template_urls_.end(); ++i) {
-    if ((*i)->prepopulate_id() == prepopulated_id)
-      return *i;
+void TemplateURLService::EnsureDefaultSearchProviderExists() {
+  if (!is_default_search_managed()) {
+    bool has_default_search_provider = default_search_provider_ &&
+        default_search_provider_->SupportsReplacement();
+    UMA_HISTOGRAM_BOOLEAN("Search.HasDefaultSearchProvider",
+                          has_default_search_provider);
+    // Ensure that default search provider exists. See http://crbug.com/116952.
+    if (!has_default_search_provider) {
+      bool success =
+          SetDefaultSearchProviderNoNotify(FindNewDefaultSearchProvider());
+      DCHECK(success);
+    }
+    // Don't log anything if the user has a NULL default search provider.
+    if (default_search_provider_) {
+      UMA_HISTOGRAM_ENUMERATION("Search.DefaultSearchProviderType",
+          TemplateURLPrepopulateData::GetEngineType(*default_search_provider_),
+          SEARCH_ENGINE_MAX);
+    }
   }
-  return NULL;
 }
 
 TemplateURL* TemplateURLService::CreateTemplateURLForExtension(
     const ExtensionKeyword& extension_keyword) {
   TemplateURLData data;
   data.short_name = base::UTF8ToUTF16(extension_keyword.extension_name);
   data.SetKeyword(base::UTF8ToUTF16(extension_keyword.extension_keyword));
   // This URL is not actually used for navigation. It holds the extension's
   // ID, as well as forcing the TemplateURL to be treated as a search keyword.
   data.SetURL(std::string(extensions::kExtensionScheme) + "://" +
       extension_keyword.extension_id + "/?q={searchTerms}");
   return new TemplateURL(profile_, data);
 }
 
 TemplateURL* TemplateURLService::FindTemplateURLForExtension(
     const std::string& extension_id,
     TemplateURL::Type type) {
   DCHECK_NE(TemplateURL::NORMAL, type);
   for (TemplateURLVector::const_iterator i = template_urls_.begin();
        i != template_urls_.end(); ++i) {
     if ((*i)->GetType() == type &&
         (*i)->GetExtensionId() == extension_id)
       return *i;
   }
+
   return NULL;
 }
 
-TemplateURL* TemplateURLService::FindMatchingExtensionTemplateURL(
-    const TemplateURLData& data,
-    TemplateURL::Type type) {
-  DCHECK_NE(TemplateURL::NORMAL, type);
-  for (TemplateURLVector::const_iterator i = template_urls_.begin();
-       i != template_urls_.end(); ++i) {
-    if ((*i)->GetType() == type && TemplateURL::MatchesData(*i, &data))
-      return *i;
-  }
-  return NULL;
-}
-
-void TemplateURLService::UpdateExtensionDefaultSearchEngine() {
+TemplateURL* TemplateURLService::FindExtensionDefaultSearchEngine() const {
   TemplateURL* most_recently_intalled_default = NULL;
   for (TemplateURLVector::const_iterator i = template_urls_.begin();
        i != template_urls_.end(); ++i) {
     if (((*i)->GetType() == TemplateURL::NORMAL_CONTROLLED_BY_EXTENSION) &&
         (*i)->extension_info_->wants_to_be_default_engine &&
         (*i)->SupportsReplacement() &&
         (!most_recently_intalled_default ||
          (most_recently_intalled_default->extension_info_->install_time <
              (*i)->extension_info_->install_time)))
       most_recently_intalled_default = *i;
   }
 
-  if (most_recently_intalled_default) {
-    base::AutoReset<DefaultSearchChangeOrigin> change_origin(
-        &dsp_change_origin_, DSP_CHANGE_OVERRIDE_SETTINGS_EXTENSION);
-    default_search_manager_.SetExtensionControlledDefaultSearchEngine(
-        most_recently_intalled_default->data());
-  } else {
-    default_search_manager_.ClearExtensionControlledDefaultSearchEngine();
+  return most_recently_intalled_default;
+}
+
+void TemplateURLService::
+    SetDefaultSearchProviderAfterRemovingDefaultExtension() {
+  DCHECK(!is_default_search_managed());
+  TemplateURL* new_dse = FindExtensionDefaultSearchEngine();
+  if (!new_dse) {
+    scoped_ptr<TemplateURLData> default_provider;
+    bool is_managed;
+    if (LoadDefaultSearchProviderFromPrefs(
+            GetPrefs(), &default_provider, &is_managed) &&
+        default_provider) {
+      for (TemplateURLVector::const_iterator i = template_urls_.begin();
+           i != template_urls_.end(); ++i) {
+        if ((*i)->id() == default_provider->id) {
+          new_dse = *i;
+          break;
+        }
+      }
+    }
   }
+  if (!new_dse)
+    new_dse = FindNewDefaultSearchProvider();
+  SetDefaultSearchProviderNoNotify(new_dse);
 }