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

chrome/browser/search/instant_service.cc

Index: chrome/browser/search/instant_service.cc
diff --git a/chrome/browser/search/instant_service.cc b/chrome/browser/search/instant_service.cc
index db35dd1dde93270be835ef9abac6cd8852c7a72a..583ece345b577e95d015aa55c0fbad29deb54c6e 100644
--- a/chrome/browser/search/instant_service.cc
+++ b/chrome/browser/search/instant_service.cc
@@ -70,11 +70,19 @@ RGBAColor SkColorToRGBAColor(const SkColor& sKColor) {
 InstantService::InstantService(Profile* profile)
     : profile_(profile),
       omnibox_start_margin_(chrome::kDisableStartMargin),
-      weak_ptr_factory_(this) {
+      weak_ptr_factory_(this),
+      current_search_result_prefetch_base_url_(
+          chrome::GetSearchResultPrefetchBaseURL(profile_)),
+      default_search_engine_watcher_(this) {
   // Stub for unit tests.
   if (!BrowserThread::CurrentlyOn(BrowserThread::UI))
     return;
 
+  TemplateURLService* template_url_service =
+      TemplateURLServiceFactory::GetForProfile(profile_);
+  if (template_url_service)
+    template_url_service->AddObserver(&default_search_engine_watcher_);
+
   ResetInstantSearchPrerenderer();
 
   registrar_.Add(this,
@@ -126,12 +134,6 @@ InstantService::InstantService(Profile* profile)
         profile_, new suggestions::SuggestionsSource(profile_));
   }
 
-  profile_pref_registrar_.Init(profile_->GetPrefs());
-  profile_pref_registrar_.Add(
-      prefs::kDefaultSearchProviderID,
-      base::Bind(&InstantService::OnDefaultSearchProviderChanged,
-                 base::Unretained(this)));
-
   registrar_.Add(this, chrome::NOTIFICATION_GOOGLE_URL_UPDATED,
                  content::Source<Profile>(profile_->GetOriginalProfile()));
 }
@@ -200,6 +202,15 @@ void InstantService::UpdateMostVisitedItemsInfo() {
   NotifyAboutMostVisitedItems();
 }
 
+InstantService::DefaultSearchEngineWatcher::DefaultSearchEngineWatcher(
+    InstantService* outer)
+    : outer_(outer) {
+}
+
+void InstantService::DefaultSearchEngineWatcher::OnTemplateURLServiceChanged() {
+  outer_->OnTemplateURLServiceChanged();
+}
+
 void InstantService::Shutdown() {
   process_ids_.clear();
 
@@ -429,9 +440,7 @@ void InstantService::OnGoogleURLUpdated(
   FOR_EACH_OBSERVER(InstantServiceObserver, observers_, GoogleURLUpdated());
 }
 
-void InstantService::OnDefaultSearchProviderChanged(
-    const std::string& pref_name) {
-  DCHECK_EQ(pref_name, std::string(prefs::kDefaultSearchProviderID));
+void InstantService::OnTemplateURLServiceChanged() {
   const TemplateURL* template_url = TemplateURLServiceFactory::GetForProfile(
       profile_)->GetDefaultSearchProvider();
   if (!template_url) {
@@ -442,6 +451,13 @@ void InstantService::OnDefaultSearchProviderChanged(
     // could cause that, neither of which we support.
     return;
   }
+  GURL new_search_result_prefetch_base_url(
+      chrome::GetSearchResultPrefetchBaseURL(profile_));
+  if (new_search_result_prefetch_base_url ==
+      current_search_result_prefetch_base_url_)
+    return;
+  current_search_result_prefetch_base_url_ =
+      new_search_result_prefetch_base_url;
 
   ResetInstantSearchPrerenderer();
 
@@ -453,9 +469,10 @@ void InstantService::ResetInstantSearchPrerenderer() {
   if (!chrome::ShouldPrefetchSearchResults())
     return;
 
-  GURL url(chrome::GetSearchResultPrefetchBaseURL(profile_));
-  if (url.is_valid())
-    instant_prerenderer_.reset(new InstantSearchPrerenderer(profile_, url));
-  else
+  if (current_search_result_prefetch_base_url_.is_valid()) {
+    instant_prerenderer_.reset(new InstantSearchPrerenderer(
+        profile_, current_search_result_prefetch_base_url_));
+  } else {
     instant_prerenderer_.reset();
+  }
 }