Eliminate NOTIFICATION_HISTORY_LOADED notification

chrome/browser/predictors/resource_prefetch_predictor.h

Index: chrome/browser/predictors/resource_prefetch_predictor.h
diff --git a/chrome/browser/predictors/resource_prefetch_predictor.h b/chrome/browser/predictors/resource_prefetch_predictor.h
index 1504370eadcad3230a58d5a1ef768c75d0144d2b..1225a22bae523045d52f5ee67786cf28eeb1d3ab 100644
--- a/chrome/browser/predictors/resource_prefetch_predictor.h
+++ b/chrome/browser/predictors/resource_prefetch_predictor.h
@@ -13,11 +13,13 @@
 #include "base/memory/linked_ptr.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/scoped_observer.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "base/time/time.h"
 #include "chrome/browser/predictors/resource_prefetch_common.h"
 #include "chrome/browser/predictors/resource_prefetch_predictor_tables.h"
 #include "chrome/browser/predictors/resource_prefetcher.h"
+#include "components/history/core/browser/history_service_observer.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "content/public/browser/notification_observer.h"
@@ -75,6 +77,7 @@ class ResourcePrefetcherManager;
 class ResourcePrefetchPredictor
     : public KeyedService,
       public content::NotificationObserver,
+      public history::HistoryServiceObserver,
       public base::SupportsWeakPtr<ResourcePrefetchPredictor> {
  public:
   // Stores the data that we need to get from the URLRequest.
@@ -293,6 +296,13 @@ class ResourcePrefetchPredictor
       size_t total_resources_fetched_from_network,
       size_t max_assumed_prefetched) const;
 
+  // history::HistoryServiceObserver:
+  void OnHistoryServiceLoaded(HistoryService* history_service) override;
+
+  // Used to connect to HistoryService or register for service loaded
+  // notificatioan.
+  void ConnectToHistoryService();
+
   // Used for testing to inject mock tables.
   void set_mock_tables(scoped_refptr<ResourcePrefetchPredictorTables> tables) {
     tables_ = tables;
@@ -316,6 +326,9 @@ class ResourcePrefetchPredictor
   ResultsMap results_map_;
   STLValueDeleter<ResultsMap> results_map_deleter_;
 
+  ScopedObserver<HistoryService, history::HistoryServiceObserver>
+      history_service_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(ResourcePrefetchPredictor);
 };