predictors: Remove unused pointer from ResourcePrefetchPredictor

ResourcePrefetchPredictor doesn't use LoadingStatsCollector since the CL
https://crrev.com/2937623007 was landed.

Bug: 715525
Change-Id: Ic16227b20fe2f3dfbd2b28e662a28f9339cc816e
Reviewed-on: https://chromium-review.googlesource.com/574606Reviewed-by: Egor Pasko <pasko@chromium.org>
Commit-Queue: Alexandr Ilin <alexilin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487167}

chrome/browser/predictors/loading_predictor.cc

@@ -30,7 +30,6 @@ LoadingPredictor::LoadingPredictor(const LoadingPredictorConfig& config,
           config)),
       observer_(nullptr),
       weak_factory_(this) {
-  resource_prefetch_predictor_->SetStatsCollector(stats_collector_.get());
   preconnect_manager_ = base::MakeUnique<PreconnectManager>(
       GetWeakPtr(), profile_->GetRequestContext());
 }

chrome/browser/predictors/resource_prefetch_predictor.cc

@@ -16,7 +16,6 @@
 #include "base/trace_event/trace_event.h"
 #include "chrome/browser/history/history_service_factory.h"
 #include "chrome/browser/predictors/loading_data_collector.h"
-#include "chrome/browser/predictors/loading_stats_collector.h"
 #include "chrome/browser/predictors/predictor_database.h"
 #include "chrome/browser/predictors/predictor_database_factory.h"
 #include "chrome/browser/profiles/profile.h"
@@ -193,7 +192,6 @@ ResourcePrefetchPredictor::ResourcePrefetchPredictor(
     Profile* profile)
     : profile_(profile),
       observer_(nullptr),
-      stats_collector_(nullptr),
       config_(config),
       initialization_state_(NOT_INITIALIZED),
       tables_(PredictorDatabaseFactory::GetForProfile(profile)
@@ -260,11 +258,6 @@ void ResourcePrefetchPredictor::SetObserverForTesting(TestObserver* observer) {
   observer_ = observer;
 }
 
-void ResourcePrefetchPredictor::SetStatsCollector(
-    LoadingStatsCollector* stats_collector) {
-  stats_collector_ = stats_collector;
-}
-
 void ResourcePrefetchPredictor::Shutdown() {
   history_service_observer_.RemoveAll();
 }

chrome/browser/predictors/resource_prefetch_predictor.h

@@ -59,7 +59,6 @@ struct LastVisitTimeCompare {
 
 class TestObserver;
 class ResourcePrefetcherManager;
-class LoadingStatsCollector;
 
 struct PreconnectPrediction {
   PreconnectPrediction();
@@ -150,9 +149,6 @@ class ResourcePrefetchPredictor : public history::HistoryServiceObserver {
   // this with nullptr parameter to de-register observer.
   void SetObserverForTesting(TestObserver* observer);
 
-  // Sets the |stats_collector| which is used to report histograms.
-  void SetStatsCollector(LoadingStatsCollector* stats_collector);
-
   // Returns true iff there is PrefetchData that can be used for a
   // |main_frame_url| and fills |prediction| with resources that need to be
   // prefetched. |prediction| pointer may be nullptr to get return value only.
@@ -293,7 +289,6 @@ class ResourcePrefetchPredictor : public history::HistoryServiceObserver {
 
   Profile* const profile_;
   TestObserver* observer_;
-  LoadingStatsCollector* stats_collector_;
   const LoadingPredictorConfig config_;
   InitializationState initialization_state_;
   scoped_refptr<ResourcePrefetchPredictorTables> tables_;