Eliminate NOTIFICATION_HISTORY_LOADED notification

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 287 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // ResourcePrefetchPredictor.
 
 ResourcePrefetchPredictor::ResourcePrefetchPredictor(
     const ResourcePrefetchPredictorConfig& config,
     Profile* profile)
     : profile_(profile),
       config_(config),
       initialization_state_(NOT_INITIALIZED),
-      tables_(PredictorDatabaseFactory::GetForProfile(
-          profile)->resource_prefetch_tables()),
-      results_map_deleter_(&results_map_) {
+      tables_(PredictorDatabaseFactory::GetForProfile(profile)
+                  ->resource_prefetch_tables()),
+      results_map_deleter_(&results_map_),
+      history_service_observer_(this) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   // Some form of learning has to be enabled.
   DCHECK(config_.IsLearningEnabled());
   if (config_.IsURLPrefetchingEnabled(profile_))
     DCHECK(config_.IsURLLearningEnabled());
   if (config_.IsHostPrefetchingEnabled(profile_))
     DCHECK(config_.IsHostLearningEnabled());
 }
 
@@ skipping 70 matching lines @@
   }
 }
 
 void ResourcePrefetchPredictor::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   switch (type) {
-    case chrome::NOTIFICATION_HISTORY_LOADED: {
-      DCHECK_EQ(initialization_state_, INITIALIZING);
-      notification_registrar_.Remove(this,
-                                     chrome::NOTIFICATION_HISTORY_LOADED,
-                                     content::Source<Profile>(profile_));
-      OnHistoryAndCacheLoaded();
-      break;
-    }
-
     case chrome::NOTIFICATION_HISTORY_URLS_DELETED: {
       DCHECK_EQ(initialization_state_, INITIALIZED);
       const content::Details<const history::URLsDeletedDetails>
           urls_deleted_details =
               content::Details<const history::URLsDeletedDetails>(details);
       if (urls_deleted_details->all_history) {
         DeleteAllUrls();
         UMA_HISTOGRAM_ENUMERATION("ResourcePrefetchPredictor.ReportingEvent",
                                   REPORTING_EVENT_ALL_HISTORY_CLEARED,
                                   REPORTING_EVENT_COUNT);
@@ skipping 267 matching lines @@
   DCHECK(inflight_navigations_.empty());
 
   url_table_cache_.reset(url_data_map.release());
   host_table_cache_.reset(host_data_map.release());
 
   UMA_HISTOGRAM_COUNTS("ResourcePrefetchPredictor.UrlTableMainFrameUrlCount",
                        url_table_cache_->size());
   UMA_HISTOGRAM_COUNTS("ResourcePrefetchPredictor.HostTableHostCount",
                        host_table_cache_->size());
 
-  // Add notifications for history loading if it is not ready.
-  HistoryService* history_service = HistoryServiceFactory::GetForProfile(
-    profile_, Profile::EXPLICIT_ACCESS);
-  if (!history_service) {
-    notification_registrar_.Add(this, chrome::NOTIFICATION_HISTORY_LOADED,
-                                content::Source<Profile>(profile_));
-  } else {
-    OnHistoryAndCacheLoaded();
-  }
+  CheckForHistoryService();
 }
 
 void ResourcePrefetchPredictor::OnHistoryAndCacheLoaded() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   DCHECK_EQ(initialization_state_, INITIALIZING);
 
   notification_registrar_.Add(this,
                               chrome::NOTIFICATION_HISTORY_URLS_DELETED,
                               content::Source<Profile>(profile_));
 
   // Initialize the prefetch manager only if prefetching is enabled.
   if (config_.IsPrefetchingEnabled(profile_)) {
     prefetch_manager_ = new ResourcePrefetcherManager(
         this, config_, profile_->GetRequestContext());
   }
 
+  history_service_observer_.RemoveAll();
   initialization_state_ = INITIALIZED;
 }
 
 void ResourcePrefetchPredictor::CleanupAbandonedNavigations(
     const NavigationID& navigation_id) {
   static const base::TimeDelta max_navigation_age =
       base::TimeDelta::FromSeconds(config_.max_navigation_lifetime_seconds);
 
   base::TimeTicks time_now = base::TimeTicks::Now();
   for (NavigationMap::iterator it = inflight_navigations_.begin();
@@ skipping 482 matching lines @@
   if (total_resources_fetched_from_network > 0) {
     RPP_PREDICTED_HISTOGRAM_PERCENTAGE(
         "PrefetchFromNetworkPercentOfTotalFromNetwork",
         prefetch_network * 100.0 / total_resources_fetched_from_network);
   }
 
 #undef RPP_PREDICTED_HISTOGRAM_PERCENTAGE
 #undef RPP_PREDICTED_HISTOGRAM_COUNTS
 }
 
+void ResourcePrefetchPredictor::CheckForHistoryService() {
+  // Register for HistoryServiceLoading if it is not ready.
+  HistoryService* history_service =
+      HistoryServiceFactory::GetForProfile(profile_, Profile::EXPLICIT_ACCESS);
+  if (!history_service)
+    return;
+  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;
+}
+
+void ResourcePrefetchPredictor::OnHistoryServiceLoaded(
+    HistoryService* history_service) {
+  OnHistoryAndCacheLoaded();
+  history_service_observer_.Remove(history_service);
+}
+
 }  // namespace predictors