Data from the autocomplete predictor wasn't deleted immediately when deleting browsing history.

chrome/browser/predictors/autocomplete_action_predictor.cc

Index: chrome/browser/predictors/autocomplete_action_predictor.cc
diff --git a/chrome/browser/predictors/autocomplete_action_predictor.cc b/chrome/browser/predictors/autocomplete_action_predictor.cc
index 90fd37d1c6711e49854d7c5977724d415fdc1517..9165cb803e3eb500caa5eaa2aa54d4be8f3d6b66 100644
--- a/chrome/browser/predictors/autocomplete_action_predictor.cc
+++ b/chrome/browser/predictors/autocomplete_action_predictor.cc
@@ -335,8 +335,7 @@ void AutocompleteActionPredictor::CreateLocalCachesFromDatabase() {
 }
 
 void AutocompleteActionPredictor::DeleteAllRows() {
-  if (!initialized_)
-    return;
+  DCHECK(initialized_);
 
   db_cache_.clear();
   db_id_cache_.clear();
@@ -353,8 +352,7 @@ void AutocompleteActionPredictor::DeleteAllRows() {
 
 void AutocompleteActionPredictor::DeleteRowsWithURLs(
     const history::URLRows& rows) {
-  if (!initialized_)
-    return;
+  DCHECK(initialized_);
 
   std::vector<AutocompleteActionPredictorTable::Row::Id> id_list;
 
@@ -442,29 +440,25 @@ void AutocompleteActionPredictor::CreateCaches(
   history::HistoryService* history_service =
       HistoryServiceFactory::GetForProfile(profile_,
                                            ServiceAccessType::EXPLICIT_ACCESS);
-  if (!TryDeleteOldEntries(history_service)) {
-    // Wait for the notification that the history service is ready and the URL
-    // DB is loaded.
-    if (history_service)
-      history_service_observer_.Add(history_service);
-  }
+  TryDeleteOldEntries(history_service);
+  if (history_service)

[pasko, 2016/12/15 15:29:48]

nit: extra check for the pointer in TryDeleteOldEntries is fine, but every
reader of these lines would have to go there and check whether it is done, which
is an expensive seek :)

this would look safer and more natural:
if (history_service) {
  TryDeleteOldEntries(history_service);
  history_service_observer_.Add(history_service);
}

+    history_service_observer_.Add(history_service);
 }
 
-bool AutocompleteActionPredictor::TryDeleteOldEntries(
+void AutocompleteActionPredictor::TryDeleteOldEntries(
     history::HistoryService* service) {
   CHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   DCHECK(!profile_->IsOffTheRecord());
   DCHECK(!initialized_);
 
   if (!service)
-    return false;
+    return;
 
   history::URLDatabase* url_db = service->InMemoryDatabase();
   if (!url_db)
-    return false;
+    return;
 
   DeleteOldEntries(url_db);
-  return true;
 }
 
 void AutocompleteActionPredictor::DeleteOldEntries(
@@ -569,8 +563,7 @@ void AutocompleteActionPredictor::OnURLsDeleted(
     bool expired,
     const history::URLRows& deleted_rows,
     const std::set<GURL>& favicon_urls) {
-  if (!initialized_)
-    return;
+  DCHECK(initialized_);
 
   if (all_history)
     DeleteAllRows();
@@ -580,8 +573,8 @@ void AutocompleteActionPredictor::OnURLsDeleted(
 
 void AutocompleteActionPredictor::OnHistoryServiceLoaded(
     history::HistoryService* history_service) {
-  TryDeleteOldEntries(history_service);
-  history_service_observer_.Remove(history_service);
+  if (!initialized_)
+    TryDeleteOldEntries(history_service);
 }
 
 AutocompleteActionPredictor::TransitionalMatch::TransitionalMatch() {