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 {
 
-const char kFirstPotentialEngineHistogramName[] =
-    "Search.FirstPotentialEngineCalled";
+bool IdenticalSyncGUIDs(const TemplateURLData* data, const TemplateURL* turl) {
+  if (!data || !turl)
+    return !data && !turl;
 
-// 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,
-};
+  return data->sync_guid == turl->sync_guid();
+}
 
 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 132 matching lines @@
   // Unfortunately the calling convention is not "prefix and element" but
   // rather "two elements", so we pass the prefix as a fake "element" which has
   // a NULL KeywordDataElement pointer.
   bool operator()(const KeywordToTemplateMap::value_type& elem1,
                   const KeywordToTemplateMap::value_type& elem2) const {
     return (elem1.second == NULL) ?
         (elem2.first.compare(0, elem1.first.length(), elem1.first) > 0) :
         (elem1.first < elem2.first);
   }
 };
 

[Peter Kasting, 2014/05/08 22:46:46]

Nit: Should still have 2 blank lines here

+// TemplateURLService ---------------------------------------------------------
 
-// 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(),
-          DefaultSearchManager::ObserverCallback()) {
+          base::Bind(&TemplateURLService::OnDefaultSearchChange,
+                     base::Unretained(this))) {
   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(),
-          DefaultSearchManager::ObserverCallback()) {
+          base::Bind(&TemplateURLService::OnDefaultSearchChange,
+                     base::Unretained(this))) {
   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) const {
-  if (!prefs || load_failed_)

[Peter Kasting, 2014/05/08 22:46:46]

The functionality that was here -- not persisting state to anywhere when in the
load failure case -- doesn't seem to be implemented anywhere in your change that
I can see.  I still think we should go into fully-nonpersistent mode when the
web DB load goes bad.  I'm worried about, for example, a user adding a new
search engine, that is given a low ID number since no other engines are loaded,
and making that engine default -- which then gets stored in prefs, and causes
dataloss when the web DB can once again load, because we blow away whatever
engine had that ID (and maybe also have dupes, if a user was trying to re-add an
existing engine).

[erikwright (departed), 2014/05/09 18:00:22]

OK - I added some new code in SetUserSelectedDefaultSearchEngine that handles
this case. 

+    PrefService* prefs) {
+  if (!prefs)
     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_ || load_failed_) &&
+  return (!loaded_ &&
       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_ || load_failed_) &&
+  return (!loaded_ &&
       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_ || 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,
                                           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)) {
-    // 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();
   }
 }
 
 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;
-  bool restore_dse = (url == GetDefaultSearchProvider());
-  if (restore_dse) {
-    DCHECK(!is_default_search_managed());
+  // NULL this out so that we can call RemoveNoNotify. The subsequent

[Peter Kasting, 2014/05/08 22:46:46]

Nit: Remove "The subsequent"

+  // 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();
 }
 
 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  !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);
+  // 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.
   if (url)
     default_search_manager_.SetUserSelectedDefaultSearchEngine(url->data());
   else
     default_search_manager_.ClearUserSelectedDefaultSearchEngine();
 }
 
 TemplateURL* TemplateURLService::GetDefaultSearchProvider() {
-  return (loaded_ && !load_failed_) ?
+  return loaded_ ?
       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() {
-  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());
 
   // 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);
   }
 
-  // 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) {
   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, &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.
   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;
-      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(
             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)));
   }
-  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
     // 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)
-        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);
   }
 }
 
 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;
-}
 
-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(
     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) {
-    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;
 }
 
 // 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::UpdateDefaultSearch() {
+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.  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;
+    // 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);
+  }
+
+  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();
+      }
+      UIThreadSearchTermsData search_terms_data(
+          default_search_provider_->profile());
+      UpdateNoNotify(default_search_provider_,
+                     TemplateURL(profile_, update_data),
+                     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);
+    } 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());
     }
 
-    initial_default_search_provider_.reset(
-        data ? new TemplateURL(profile_, *data) : NULL);
+  }
 
-    return;
+  default_search_provider_source_ = source;
+
+  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);
+#endif
   }
-  // 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;
-  }
-  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);
-      UIThreadSearchTermsData search_terms_data(
-          default_search_provider_->profile());
-      UpdateNoNotify(default_search_provider_, new_values, 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);
-    }
-  } 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 {
-      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);
-#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;
-}
-
 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());
     template_url->data_.id = ++next_id_;
   }
@@ skipping 92 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, new_url, search_terms_data);
+  return UpdateNoNotify(url, TemplateURL(profile_, data), 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_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());
       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);
+    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, new_url, search_terms_data);
+  UpdateNoNotify(url, TemplateURL(profile_, data), 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, 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
   // 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;
-    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);
   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::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);
+void TemplateURLService::OnSyncedDefaultSearchProviderGUIDChanged() {
+  base::AutoReset<DefaultSearchChangeOrigin> change_origin(
+      &dsp_change_origin_, DSP_CHANGE_SYNC_PREF);
 
-  // Check if default search provider is now managed.
-  scoped_ptr<TemplateURLData> default_from_prefs;
-  LoadDefaultSearchProviderFromPrefs(
-      GetPrefs(), &default_from_prefs, &is_default_search_managed_);
+  std::string new_guid =
+      GetPrefs()->GetString(prefs::kSyncedDefaultSearchProviderGUID);
+  if (new_guid.empty()) {
+    default_search_manager_.ClearUserSelectedDefaultSearchEngine();
+    return;
+  }
 
-  // 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());
 }
 
-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;
   }
+

[Peter Kasting, 2014/05/08 22:46:46]

Nit: I'd probably omit the blank line here (and in the similar find functions
below), but up to you.

+  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::FindExtensionDefaultSearchEngine() const {
+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* 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;
   }
 
-  return most_recently_intalled_default;
+  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();
+  }
 }
-
-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);
-}