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

chrome/browser/search_engines/template_url_service.cc

Index: chrome/browser/search_engines/template_url_service.cc
diff --git a/chrome/browser/search_engines/template_url_service.cc b/chrome/browser/search_engines/template_url_service.cc
index c6c9a421a00341da7bb67474abf7011551b7abca..9999ff58695b90ac52c2533c36a83295deaad7dc 100644
--- a/chrome/browser/search_engines/template_url_service.cc
+++ b/chrome/browser/search_engines/template_url_service.cc
@@ -58,19 +58,12 @@ typedef TemplateURLService::SyncDataMap SyncDataMap;
 
 namespace {
 
-const char kFirstPotentialEngineHistogramName[] =
-    "Search.FirstPotentialEngineCalled";
-
-// 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,
-};
+bool IdenticalSyncGUIDs(const TemplateURLData* data, const TemplateURL* turl) {
+  if (!data || !turl)
+    return !data && !turl;
+
+  return data->sync_guid == turl->sync_guid();
+}
 
 const char kDeleteSyncedEngineHistogramName[] =
     "Search.DeleteSyncedSearchEngine";
@@ -84,17 +77,6 @@ enum DeleteSyncedSearchEngineEvent {
   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|.
@@ -251,6 +233,9 @@ class TemplateURLService::LessWithPrefix {
 
 // TemplateURLService ---------------------------------------------------------
 
+// static
+bool TemplateURLService::g_fallback_search_engines_disabled = false;
+
 TemplateURLService::TemplateURLService(Profile* profile)
     : provider_map_(new SearchHostToURLsMap),
       profile_(profile),
@@ -258,15 +243,15 @@ TemplateURLService::TemplateURLService(Profile* profile)
       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(), DefaultSearchManager::ObserverCallback()) {
+          GetPrefs(),
+          base::Bind(&TemplateURLService::OnDefaultSearchChange,
+                     base::Unretained(this))) {
   DCHECK(profile_);
   Init(NULL, 0);
 }
@@ -280,15 +265,15 @@ TemplateURLService::TemplateURLService(const Initializer* initializers,
       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(), DefaultSearchManager::ObserverCallback()) {
+          GetPrefs(),
+          base::Bind(&TemplateURLService::OnDefaultSearchChange,
+                     base::Unretained(this))) {
   Init(initializers, count);
 }
 
@@ -473,10 +458,11 @@ GURL TemplateURLService::GenerateSearchURLUsingTermsData(
       search_terms_data, NULL));
 }
 
+// static
 void TemplateURLService::SaveDefaultSearchProviderToPrefs(
     const TemplateURL* t_url,
-    PrefService* prefs) const {
-  if (!prefs || load_failed_)
+    PrefService* prefs) {
+  if (!prefs)
     return;
 
   bool enabled = false;
@@ -608,7 +594,7 @@ TemplateURL* TemplateURLService::GetTemplateURLForKeyword(
       keyword_to_template_map_.find(keyword));
   if (elem != keyword_to_template_map_.end())
     return elem->second;
-  return ((!loaded_ || load_failed_) &&
+  return (!loaded_ &&
       initial_default_search_provider_.get() &&
       (initial_default_search_provider_->keyword() == keyword)) ?
       initial_default_search_provider_.get() : NULL;
@@ -619,7 +605,7 @@ TemplateURL* TemplateURLService::GetTemplateURLForGUID(
   GUIDToTemplateMap::const_iterator elem(guid_to_template_map_.find(sync_guid));
   if (elem != guid_to_template_map_.end())
     return elem->second;
-  return ((!loaded_ || load_failed_) &&
+  return (!loaded_ &&
       initial_default_search_provider_.get() &&
       (initial_default_search_provider_->sync_guid() == sync_guid)) ?
       initial_default_search_provider_.get() : NULL;
@@ -632,16 +618,18 @@ TemplateURL* TemplateURLService::GetTemplateURLForHost(
     if (t_url)
       return t_url;
   }
-  return ((!loaded_ || load_failed_) &&
+  return (!loaded_ &&
       initial_default_search_provider_.get() &&
       (GenerateSearchURL(initial_default_search_provider_.get()).host() ==
           host)) ? initial_default_search_provider_.get() : NULL;
 }
 
-void TemplateURLService::Add(TemplateURL* template_url) {
+bool TemplateURLService::Add(TemplateURL* template_url) {
   WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
-  if (AddNoNotify(template_url, true))
-    NotifyObservers();
+  if (!AddNoNotify(template_url, true))
+    return false;
+  NotifyObservers();
+  return true;
 }
 
 void TemplateURLService::AddAndSetProfile(TemplateURL* template_url,
@@ -678,18 +666,8 @@ void TemplateURLService::AddExtensionControlledTURL(
 
   WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
   if (AddNoNotify(template_url, true)) {
-    // 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);
-      }
-    }
+    if (template_url->extension_info_->wants_to_be_default_engine)
+      UpdateExtensionDefaultSearchEngine();
     NotifyObservers();
   }
 }
@@ -706,15 +684,13 @@ void TemplateURLService::RemoveExtensionControlledTURL(
       extension_id, TemplateURL::NORMAL_CONTROLLED_BY_EXTENSION);
   if (!url)
     return;
-  bool restore_dse = (url == GetDefaultSearchProvider());
-  if (restore_dse) {
-    DCHECK(!is_default_search_managed());
+  // NULL this out so that we can call RemoveNoNotify.
+  // UpdateExtensionDefaultSearchEngine will cause it to be reset.
+  if (default_search_provider_ == url)
     default_search_provider_ = NULL;
-  }
   WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
   RemoveNoNotify(url);
-  if (restore_dse)
-    SetDefaultSearchProviderAfterRemovingDefaultExtension();
+  UpdateExtensionDefaultSearchEngine();
   NotifyObservers();
 }
 
@@ -801,24 +777,39 @@ void TemplateURLService::ResetTemplateURL(TemplateURL* url,
 }
 
 bool TemplateURLService::CanMakeDefault(const TemplateURL* url) {
-  return  !is_default_search_managed() &&
-      !IsExtensionControlledDefaultSearch() &&
-      (url != GetDefaultSearchProvider()) &&
-      url->url_ref().SupportsReplacement() &&
-      (url->GetType() == TemplateURL::NORMAL);
+  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);
 }
 
 void TemplateURLService::SetUserSelectedDefaultSearchProvider(
     TemplateURL* url) {
-  SetDefaultSearchProvider(url);
-  if (url)
-    default_search_manager_.SetUserSelectedDefaultSearchEngine(url->data());
-  else
+  // 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));
+  // We rely on the DefaultSearchManager to push this back to us if, in fact,
+  // the effective DSE changes.

[Peter Kasting, 2014/05/09 19:12:49]

This comment doesn't make it clear what, precisely, is going to get "pushed
back" in the DSM cases, and whether that's equivalent to the call to
ApplyDefaultSearchChange() or not.  Might want to update it.

+  if (load_failed_) {
+    if ((default_search_provider_source_ == DefaultSearchManager::FROM_USER) ||

[Peter Kasting, 2014/05/09 19:12:49]

Consider a comment here about what this does differently than the calls below
and why it makes sense to do it in the failure case, unless the updated comment
above covers this.

+        (default_search_provider_source_ ==
+         DefaultSearchManager::FROM_FALLBACK)) {
+      ApplyDefaultSearchChange(url ? &url->data() : NULL,
+                               DefaultSearchManager::FROM_USER);
+    }
+  } else if (url) {
+      default_search_manager_.SetUserSelectedDefaultSearchEngine(url->data());

[Peter Kasting, 2014/05/09 19:12:49]

Nit: Indent 2, not 4

+  } else {
     default_search_manager_.ClearUserSelectedDefaultSearchEngine();
+  }
 }
 
 TemplateURL* TemplateURLService::GetDefaultSearchProvider() {
-  return (loaded_ && !load_failed_) ?
+  return loaded_ ?
       default_search_provider_ : initial_default_search_provider_.get();
 }
 
@@ -829,59 +820,29 @@ bool TemplateURLService::IsSearchResultsPageFromDefaultSearchProvider(
 }
 
 bool TemplateURLService::IsExtensionControlledDefaultSearch() {
-  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_);
+  return default_search_provider_source_ ==
+      DefaultSearchManager::FROM_EXTENSION;
 }
 
 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_, current_dse));
+      &prepopulated_urls, template_urls_, default_search_provider_));
 
   WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
 
@@ -906,16 +867,20 @@ void TemplateURLService::RepairPrepopulatedSearchEngines() {
     AddNoNotify(new TemplateURL(profile_, *i), true);
   }
 
-  // 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);
+  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();
   }
-  NotifyObservers();
 }
 
 void TemplateURLService::AddObserver(TemplateURLServiceObserver* observer) {
@@ -933,12 +898,10 @@ void TemplateURLService::Load() {
   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>
@@ -962,27 +925,29 @@ void TemplateURLService::OnWebDataServiceRequestDone(
     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, &new_resource_keyword_version,
+  GetSearchProvidersUsingKeywordResult(
+      *result,
+      service_.get(),
+      profile_,
+      &template_urls,
+      (default_search_provider_source_ == DefaultSearchManager::FROM_USER) ?
+          initial_default_search_provider_.get() : NULL,
+      &new_resource_keyword_version,
       &pre_sync_deletes_);
 
   WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
 
-  AddTemplateURLsAndSetupDefaultEngine(&template_urls, default_search_provider);
+  PatchMissingSyncGUIDs(&template_urls);
+  SetTemplateURLs(&template_urls);
 
   // 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.
@@ -992,11 +957,6 @@ void TemplateURLService::OnWebDataServiceRequestDone(
 
   if (new_resource_keyword_version)
     service_->SetBuiltinKeywordVersion(new_resource_keyword_version);
-
-  EnsureDefaultSearchProviderExists();
-
-  NotifyObservers();
-  on_loaded_callbacks_.Notify();
 }
 
 base::string16 TemplateURLService::GetKeywordShortName(
@@ -1024,12 +984,6 @@ void TemplateURLService::Observe(int type,
       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_) {
@@ -1050,27 +1004,6 @@ void TemplateURLService::Shutdown() {
   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);
@@ -1186,13 +1119,14 @@ syncer::SyncError TemplateURLService::ProcessSyncChanges(
         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;
-      Add(new TemplateURL(profile_, data));
-
-      // Possibly set the newly added |turl| as the default search provider.
-      SetDefaultSearchProviderIfNewlySynced(guid);
+      TemplateURL* added = new TemplateURL(profile_, data);
+      if (Add(added))
+        MaybeUpdateDSEAfterSync(added);
     } else if (iter->change_type() == syncer::SyncChange::ACTION_UPDATE) {
       if (!existing_turl) {
         error = sync_error_factory_->CreateAndUploadError(
@@ -1207,8 +1141,10 @@ syncer::SyncError TemplateURLService::ProcessSyncChanges(
                                    &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(
@@ -1250,18 +1186,6 @@ syncer::SyncMergeResult TemplateURLService::MergeDataAndStartSyncing(
   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);
@@ -1340,15 +1264,6 @@ syncer::SyncMergeResult TemplateURLService::MergeDataAndStartSyncing(
     }
   }
 
-  // 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();
@@ -1600,9 +1515,11 @@ void TemplateURLService::Init(const Initializer* initializers,
             &TemplateURLService::OnSyncedDefaultSearchProviderGUIDChanged,
             base::Unretained(this)));
   }
-  notification_registrar_.Add(
-      this, chrome::NOTIFICATION_DEFAULT_SEARCH_POLICY_CHANGED,
-      content::NotificationService::AllSources());
+
+  DefaultSearchManager::Source source = DefaultSearchManager::FROM_USER;
+  TemplateURLData* dse =
+      default_search_manager_.GetDefaultSearchEngine(&source);
+  ApplyDefaultSearchChange(dse, source);
 
   if (num_initializers > 0) {
     // This path is only hit by test code and is used to simulate a loaded
@@ -1627,17 +1544,15 @@ void TemplateURLService::Init(const Initializer* initializers,
 
       // Set the first provided identifier to be the default.
       if (i == 0)
-        SetDefaultSearchProviderNoNotify(template_url);
+        default_search_manager_.SetUserSelectedDefaultSearchEngine(data);
     }
   }
 
-  // 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.
-  if (profile_ && initial_default_search_provider_ &&
-      initial_default_search_provider_->HasGoogleBaseURLs()) {
+  TemplateURL* default_search_provider = GetDefaultSearchProvider();
+  if (profile_ && default_search_provider &&
+      default_search_provider->HasGoogleBaseURLs()) {
     scoped_ptr<base::Environment> env(base::Environment::Create());
     if (!env->HasVar(env_vars::kHeadless))
       GoogleURLTracker::RequestServerCheck(profile_, false);
@@ -1750,16 +1665,13 @@ void TemplateURLService::ChangeToLoadedState() {
   UIThreadSearchTermsData search_terms_data(profile_);
   provider_map_->Init(template_urls_, search_terms_data);
   loaded_ = true;
-}
 
-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);
+  // 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();
 }
 
 bool TemplateURLService::CanReplaceKeywordForHost(
@@ -1856,13 +1768,13 @@ bool TemplateURLService::UpdateNoNotify(
     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) {
-    bool success = SetDefaultSearchProviderNoNotify(existing_turl);
-    DCHECK(success);
+  if (default_search_provider_ == existing_turl &&
+      default_search_provider_source_ == DefaultSearchManager::FROM_USER) {
+    default_search_manager_.SetUserSelectedDefaultSearchEngine(
+        default_search_provider_->data());
   }
   return true;
 }
@@ -1888,6 +1800,15 @@ void TemplateURLService::UpdateTemplateURLIfPrepopulated(
   }
 }
 
+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;
 }
@@ -1985,204 +1906,134 @@ void TemplateURLService::GoogleBaseURLChanged(const GURL& old_base_url) {
     NotifyObservers();
 }
 
-void TemplateURLService::UpdateDefaultSearch() {
-  if (!loaded_) {
-    // 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;
-    }
+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) {
+  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.
     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))
     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);
   }
-  // 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.
+
+  if (!data) {
+    default_search_provider_ = NULL;
+    default_search_provider_source_ = source;
+    NotifyObservers();
     return;
   }
-  WebDataService::KeywordBatchModeScoper keyword_scoper(service_.get());
-  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);
+
+  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();
+      }
       UIThreadSearchTermsData search_terms_data(
           default_search_provider_->profile());
-      UpdateNoNotify(default_search_provider_, new_values, search_terms_data);
+      UpdateNoNotify(default_search_provider_,
+                     TemplateURL(profile_, update_data),
+                     search_terms_data);
     } else {
-      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);
+      // 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;
     }
-  } 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);
+  }
+  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);
     }
-
-    // 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);
+    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);
     } else {
-      SetDefaultSearchProviderNoNotify(FindNewDefaultSearchProvider());
+      new_data.id = kInvalidTemplateURLID;
+      TemplateURL* new_dse = new TemplateURL(profile_, new_data);
+      if (AddNoNotify(new_dse, true))
+        default_search_provider_ = new_dse;
     }
-  }
-  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 (default_search_provider_ && GetPrefs()) {
+      GetPrefs()->SetString(
+          prefs::kSyncedDefaultSearchProviderGUID,
+          default_search_provider_->sync_guid());
     }
+
   }
 
-  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());
+  default_search_provider_source_ = source;
 
-    if (url->HasGoogleBaseURLs()) {
+  if (default_search_provider_ &&
+      default_search_provider_->HasGoogleBaseURLs()) {
+    if (profile_)
       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
-    }
   }
 
-  // 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;
+  NotifyObservers();
 }
 
 bool TemplateURLService::AddNoNotify(TemplateURL* template_url,
@@ -2297,9 +2148,8 @@ bool TemplateURLService::ResetTemplateURLNoNotify(
   }
   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, new_url, search_terms_data);
+  return UpdateNoNotify(url, TemplateURL(profile_, data), search_terms_data);
 }
 
 void TemplateURLService::NotifyObservers() {
@@ -2311,41 +2161,35 @@ void TemplateURLService::NotifyObservers() {
 }
 
 // |template_urls| are the TemplateURLs loaded from the database.
-// |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.
+// |default_from_prefs| is the default search provider from the preferences, or
+// NULL if the DSE is not policy-defined.
 //
 // 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
-// and matches what is set by a managed preference.
-void TemplateURLService::RemoveProvidersCreatedByPolicy(
+// 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(
     TemplateURLVector* template_urls,
-    TemplateURL** default_search_provider,
-    TemplateURLData* default_from_prefs) {
+    const 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 (template_url == *default_search_provider &&
-          is_default_search_managed_ &&
+      if (default_from_prefs &&
           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;
       }
 
-      // 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;
-
+      RemoveFromMaps(template_url);
       i = template_urls->erase(i);
       if (service_)
         service_->RemoveKeyword(template_url->id());
@@ -2354,6 +2198,18 @@ void TemplateURLService::RemoveProvidersCreatedByPolicy(
       ++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,
@@ -2363,9 +2219,8 @@ void TemplateURLService::ResetTemplateURLGUID(TemplateURL* url,
 
   TemplateURLData data(url->data());
   data.sync_guid = guid;
-  TemplateURL new_url(url->profile(), data);
   UIThreadSearchTermsData search_terms_data(url->profile());
-  UpdateNoNotify(url, new_url, search_terms_data);
+  UpdateNoNotify(url, TemplateURL(profile_, data), search_terms_data);
 }
 
 base::string16 TemplateURLService::UniquifyKeyword(const TemplateURL& turl,
@@ -2436,9 +2291,9 @@ void TemplateURLService::ResolveSyncKeywordConflict(
     // 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, new_turl, search_terms_data))
+    if (UpdateNoNotify(
+            applied_sync_turl, TemplateURL(profile_, data), search_terms_data))
       NotifyObservers();
   }
   // The losing TemplateURL should have their keyword updated. Send a change to
@@ -2487,18 +2342,6 @@ void TemplateURLService::MergeInSyncTemplateURL(
             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.
@@ -2523,43 +2366,16 @@ void TemplateURLService::MergeInSyncTemplateURL(
     // Force the local ID to kInvalidTemplateURLID so we can add it.
     TemplateURLData data(sync_turl->data());
     data.id = kInvalidTemplateURLID;
-    Add(new TemplateURL(profile_, data));
+    TemplateURL* added = new TemplateURL(profile_, data);
+    base::AutoReset<DefaultSearchChangeOrigin> change_origin(
+        &dsp_change_origin_, DSP_CHANGE_SYNC_ADD);
+    if (Add(added))
+      MaybeUpdateDSEAfterSync(added);
     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);
@@ -2577,112 +2393,30 @@ void TemplateURLService::PatchMissingSyncGUIDs(
   }
 }
 
-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);
-
-  // 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);
+void TemplateURLService::OnSyncedDefaultSearchProviderGUIDChanged() {
+  base::AutoReset<DefaultSearchChangeOrigin> change_origin(
+      &dsp_change_origin_, DSP_CHANGE_SYNC_PREF);
 
-    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());
-    }
+  std::string new_guid =
+      GetPrefs()->GetString(prefs::kSyncedDefaultSearchProviderGUID);
+  if (new_guid.empty()) {
+    default_search_manager_.ClearUserSelectedDefaultSearchEngine();
+    return;
   }
+
+  TemplateURL* turl = GetTemplateURLForGUID(new_guid);
+  if (turl)
+    default_search_manager_.SetUserSelectedDefaultSearchEngine(turl->data());
 }
 
-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);
-    }
+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;
   }
+  return NULL;
 }
 
 TemplateURL* TemplateURLService::CreateTemplateURLForExtension(
@@ -2707,11 +2441,22 @@ TemplateURL* TemplateURLService::FindTemplateURLForExtension(
         (*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;
 }
 
-TemplateURL* TemplateURLService::FindExtensionDefaultSearchEngine() const {
+void TemplateURLService::UpdateExtensionDefaultSearchEngine() {
   TemplateURL* most_recently_intalled_default = NULL;
   for (TemplateURLVector::const_iterator i = template_urls_.begin();
        i != template_urls_.end(); ++i) {
@@ -2724,29 +2469,12 @@ TemplateURL* TemplateURLService::FindExtensionDefaultSearchEngine() const {
       most_recently_intalled_default = *i;
   }
 
-  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 (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();
   }
-  if (!new_dse)
-    new_dse = FindNewDefaultSearchProvider();
-  SetDefaultSearchProviderNoNotify(new_dse);
 }