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

chrome/browser/predictors/resource_prefetch_predictor.cc

 // Copyright 2014 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/predictors/resource_prefetch_predictor.h"
 
 #include <map>
 #include <set>
 #include <utility>
 
@@ skipping 1125 matching lines @@
   } else {
     DeleteUrls(deleted_rows);
     UMA_HISTOGRAM_ENUMERATION("ResourcePrefetchPredictor.ReportingEvent",
                               REPORTING_EVENT_PARTIAL_HISTORY_CLEARED,
                               REPORTING_EVENT_COUNT);
   }
 }
 
 void ResourcePrefetchPredictor::OnHistoryServiceLoaded(
     history::HistoryService* history_service) {
-  OnHistoryAndCacheLoaded();
-  history_service_observer_.Remove(history_service);
+  if (initialization_state_ == INITIALIZING) {
+    OnHistoryAndCacheLoaded();

[pasko, 2016/11/29 18:01:00]

Would it be possible for HistoryServiceFactory::GetForProfile to return nullptr
while we were initializing? This would skip calling OnHistoryAndCacheLoaded()
entirely, right? Am I missing something?

Can the async tasks be simplified to only record the flag that they were loaded
and call the continuation that does the job only if all init bits are set? I
believe that would simplify the spaghetti a bit.

[dullweber, 2016/11/30 11:49:21]

I added this check for the same rare reason as for initialized_ in the  other
file.

+  }
 }
 
 void ResourcePrefetchPredictor::ConnectToHistoryService() {
   // Register for HistoryServiceLoading if it is not ready.
   history::HistoryService* history_service =
       HistoryServiceFactory::GetForProfile(profile_,
                                            ServiceAccessType::EXPLICIT_ACCESS);
   if (!history_service)
     return;
+  DCHECK(!history_service_observer_.IsObserving(history_service));
+  history_service_observer_.Add(history_service);
   if (history_service->BackendLoaded()) {
     // HistoryService is already loaded. Continue with Initialization.
     OnHistoryAndCacheLoaded();
-    return;
   }
-  DCHECK(!history_service_observer_.IsObserving(history_service));
-  history_service_observer_.Add(history_service);
-  return;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // TestObserver.
 
 TestObserver::~TestObserver() {
   predictor_->SetObserverForTesting(nullptr);
 }
 
 TestObserver::TestObserver(ResourcePrefetchPredictor* predictor)
     : predictor_(predictor) {
   predictor_->SetObserverForTesting(this);
 }
 
 }  // namespace predictors