Create LoadingDataCollector class and have observers rely on it instead of ResourcePrefetchPredictor

chrome/browser/predictors/loading_stats_collector_unittest.cc

 // Copyright 2017 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/loading_stats_collector.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/test/histogram_tester.h"
-#include "chrome/browser/predictors/resource_prefetch_predictor_test_util.h"
+#include "chrome/browser/predictors/loading_test_util.h"
 #include "chrome/test/base/testing_profile.h"
 #include "content/public/test/test_browser_thread_bundle.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using testing::_;
 using testing::DoAll;
 using testing::Return;
 using testing::SetArgPointee;
 using testing::StrictMock;
 
@@ skipping 181 matching lines @@
       internal::kResourcePrefetchPredictorPrefetchHitsCountCached, 1, 1);
   histogram_tester_->ExpectUniqueSample(
       internal::kResourcePrefetchPredictorPrefetchHitsCountNotCached, 1, 1);
   histogram_tester_->ExpectUniqueSample(
       internal::kResourcePrefetchPredictorPrefetchHitsSize, 50, 1);
   histogram_tester_->ExpectUniqueSample(
       internal::kResourcePrefetchPredictorPrefetchMissesSize, 5, 1);
 }
 
 }  // namespace predictors