Rework UMAHistogramHelper and StatisticsDeltaReader into [Chrome]HistogramTester.

net/url_request/url_request_throttler_unittest.cc

 // Copyright (c) 2012 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 "net/url_request/url_request_throttler_manager.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram_samples.h"
 #include "base/pickle.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
-#include "base/test/statistics_delta_reader.h"
+#include "base/test/histogram_tester.h"
 #include "base/time/time.h"
 #include "net/base/load_flags.h"
 #include "net/base/request_priority.h"
 #include "net/base/test_completion_callback.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_test_util.h"
 #include "net/url_request/url_request_throttler_header_interface.h"
 #include "net/url_request/url_request_throttler_test_support.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 176 matching lines @@
   entry_->set_exponential_backoff_release_time(
       entry_->fake_time_now_ + TimeDelta::FromMilliseconds(1));
 
   d.set_can_throttle_requests(false);
   EXPECT_FALSE(entry_->ShouldRejectRequest(request_));
   d.set_can_throttle_requests(true);
   EXPECT_TRUE(entry_->ShouldRejectRequest(request_));
 }
 
 TEST_F(URLRequestThrottlerEntryTest, InterfaceDuringExponentialBackoff) {
-  base::StatisticsDeltaReader statistics_delta_reader;
+  base::HistogramTester histogram_tester;
   entry_->set_exponential_backoff_release_time(
       entry_->fake_time_now_ + TimeDelta::FromMilliseconds(1));
   EXPECT_TRUE(entry_->ShouldRejectRequest(request_));
 
   // Also end-to-end test the load flags exceptions.
   request_.SetLoadFlags(LOAD_MAYBE_USER_GESTURE);
   EXPECT_FALSE(entry_->ShouldRejectRequest(request_));
 
-  scoped_ptr<base::HistogramSamples> samples(
-      statistics_delta_reader.GetHistogramSamplesSinceCreation(
-          kRequestThrottledHistogramName));
-  ASSERT_EQ(1, samples->GetCount(0));
-  ASSERT_EQ(1, samples->GetCount(1));
+  histogram_tester.ExpectBucketCount(kRequestThrottledHistogramName, 0, 1);
+  histogram_tester.ExpectBucketCount(kRequestThrottledHistogramName, 1, 1);
 }
 
 TEST_F(URLRequestThrottlerEntryTest, InterfaceNotDuringExponentialBackoff) {
-  base::StatisticsDeltaReader statistics_delta_reader;
+  base::HistogramTester histogram_tester;
   entry_->set_exponential_backoff_release_time(entry_->fake_time_now_);
   EXPECT_FALSE(entry_->ShouldRejectRequest(request_));
   entry_->set_exponential_backoff_release_time(
       entry_->fake_time_now_ - TimeDelta::FromMilliseconds(1));
   EXPECT_FALSE(entry_->ShouldRejectRequest(request_));
 
-  scoped_ptr<base::HistogramSamples> samples(
-      statistics_delta_reader.GetHistogramSamplesSinceCreation(
-          kRequestThrottledHistogramName));
-  ASSERT_EQ(2, samples->GetCount(0));
-  ASSERT_EQ(0, samples->GetCount(1));
+  histogram_tester.ExpectBucketCount(kRequestThrottledHistogramName, 0, 2);
+  histogram_tester.ExpectBucketCount(kRequestThrottledHistogramName, 1, 0);
 }
 
 TEST_F(URLRequestThrottlerEntryTest, InterfaceUpdateFailure) {
   MockURLRequestThrottlerHeaderAdapter failure_response(503);
   entry_->UpdateWithResponse(std::string(), &failure_response);
   EXPECT_GT(entry_->GetExponentialBackoffReleaseTime(), entry_->fake_time_now_)
       << "A failure should increase the release_time";
 }
 
 TEST_F(URLRequestThrottlerEntryTest, InterfaceUpdateSuccess) {
@@ skipping 268 matching lines @@
         FAIL();
     }
 
     scoped_refptr<net::URLRequestThrottlerEntryInterface> entry_after =
         manager.RegisterRequestUrl(GURL("http://www.example.com/"));
     EXPECT_FALSE(entry_after->ShouldRejectRequest(request_));
   }
 }
 
 }  // namespace net