Revert 242121 "Reland "Add a HistogramRecorder class and use cas..."

As per request from lpromero, reverting since it might be failing a
test - see

http://build.chromium.org/p/chromium.memory.fyi/builders/Windows%20Tests%20%28tsan%29/builds/17153/steps/memory%20test%3A%20base_unittests/logs/stdio

[ RUN      ] HistogramTest.BasicTest
[3824:2780:1220/111332:4747750:FATAL:statistics_recorder.cc(270)] Check failed: !histograms_.

TBR=lpromero@chromium.org

> Reland "Add a HistogramRecorder class and use cases."
> 
> This CL adds a utility class to streamline the task of testing that metrics have been updated as expected. Specifically, the HistogramRecorder class allows a client to obtain the differential value of a given histogram in the interval since the given HistogramRecorder instance was created.
> 
> This reverts commit b957026f43ef9464a8cdd5a240867c807b2281da.
> 
> BUG=232414
> TBR=rsleevi, mark, groby, thakis
> 
> Review URL: https://codereview.chromium.org/19866004

TBR=lpromero@chromium.org

Review URL: https://codereview.chromium.org/120273002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242176 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 64 insertions, 18 deletions

diff --git a/net/url_request/url_request_throttler_unittest.cc b/net/url_request/url_request_throttler_unittest.cc
index 52b3a0a..b964b10 100644
--- a/net/url_request/url_request_throttler_unittest.cc
+++ b/net/url_request/url_request_throttler_unittest.cc
@@ -5,12 +5,13 @@
 #include "net/url_request/url_request_throttler_manager.h"
 
 #include "base/memory/scoped_ptr.h"
+#include "base/metrics/histogram.h"
 #include "base/metrics/histogram_samples.h"
+#include "base/metrics/statistics_recorder.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/histogram_recorder.h"
 #include "base/time/time.h"
 #include "net/base/load_flags.h"
 #include "net/base/request_priority.h"
@@ -28,7 +29,10 @@ namespace net {
 
 namespace {
 
-const char kRequestThrottledHistogramName[] = "Throttling.RequestThrottled";
+using base::Histogram;
+using base::HistogramBase;
+using base::HistogramSamples;
+using base::StatisticsRecorder;
 
 class MockURLRequestThrottlerEntry : public URLRequestThrottlerEntry {
  public:
@@ -172,22 +176,32 @@ class URLRequestThrottlerEntryTest : public testing::Test {
   URLRequestThrottlerEntryTest()
       : request_(GURL(), DEFAULT_PRIORITY, NULL, &context_) {}
 
-  static void SetUpTestCase() {
-    base::HistogramRecorder::Initialize();
-  }
-
   virtual void SetUp();
+  virtual void TearDown();
+
+  // After calling this function, histogram snapshots in |samples_| contain
+  // only the delta caused by the test case currently running.
+  void CalculateHistogramDeltas();
 
   TimeTicks now_;
   MockURLRequestThrottlerManager manager_;  // Dummy object, not used.
   scoped_refptr<MockURLRequestThrottlerEntry> entry_;
 
-  scoped_ptr<base::HistogramRecorder> histogram_recorder_;
+  std::map<std::string, HistogramSamples*> original_samples_;
+  std::map<std::string, HistogramSamples*> samples_;
 
   TestURLRequestContext context_;
   TestURLRequest request_;
 };
 
+// List of all histograms we care about in these unit tests.
+const char* kHistogramNames[] = {
+  "Throttling.FailureCountAtSuccess",
+  "Throttling.PerceivedDowntime",
+  "Throttling.RequestThrottled",
+  "Throttling.SiteOptedOut",
+};
+
 void URLRequestThrottlerEntryTest::SetUp() {
   request_.SetLoadFlags(0);
 
@@ -195,7 +209,43 @@ void URLRequestThrottlerEntryTest::SetUp() {
   entry_ = new MockURLRequestThrottlerEntry(&manager_);
   entry_->ResetToBlank(now_);
 
-  histogram_recorder_.reset(new base::HistogramRecorder());
+  for (size_t i = 0; i < arraysize(kHistogramNames); ++i) {
+    // Must retrieve original samples for each histogram for comparison
+    // as other tests may affect them.
+    const char* name = kHistogramNames[i];
+    HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
+    if (histogram) {
+      original_samples_[name] = histogram->SnapshotSamples().release();
+    } else {
+      original_samples_[name] = NULL;
+    }
+  }
+}
+
+void URLRequestThrottlerEntryTest::TearDown() {
+  STLDeleteValues(&original_samples_);
+  STLDeleteValues(&samples_);
+}
+
+void URLRequestThrottlerEntryTest::CalculateHistogramDeltas() {
+  for (size_t i = 0; i < arraysize(kHistogramNames); ++i) {
+    const char* name = kHistogramNames[i];
+    HistogramSamples* original = original_samples_[name];
+
+    HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
+    if (histogram) {
+      ASSERT_EQ(HistogramBase::kUmaTargetedHistogramFlag, histogram->flags());
+
+      scoped_ptr<HistogramSamples> samples(histogram->SnapshotSamples());
+      if (original)
+        samples->Subtract(*original);
+      samples_[name] = samples.release();
+    }
+  }
+
+  // Ensure we don't accidentally use the originals in our tests.
+  STLDeleteValues(&original_samples_);
+  original_samples_.clear();
 }
 
 std::ostream& operator<<(std::ostream& out, const base::TimeTicks& time) {
@@ -223,11 +273,9 @@ TEST_F(URLRequestThrottlerEntryTest, InterfaceDuringExponentialBackoff) {
   request_.SetLoadFlags(LOAD_MAYBE_USER_GESTURE);
   EXPECT_FALSE(entry_->ShouldRejectRequest(request_));
 
-  scoped_ptr<base::HistogramSamples> samples(
-      histogram_recorder_->GetHistogramSamplesSinceCreation(
-          kRequestThrottledHistogramName));
-  ASSERT_EQ(1, samples->GetCount(0));
-  ASSERT_EQ(1, samples->GetCount(1));
+  CalculateHistogramDeltas();
+  ASSERT_EQ(1, samples_["Throttling.RequestThrottled"]->GetCount(0));
+  ASSERT_EQ(1, samples_["Throttling.RequestThrottled"]->GetCount(1));
 }
 
 TEST_F(URLRequestThrottlerEntryTest, InterfaceNotDuringExponentialBackoff) {
@@ -237,11 +285,9 @@ TEST_F(URLRequestThrottlerEntryTest, InterfaceNotDuringExponentialBackoff) {
       entry_->fake_time_now_ - TimeDelta::FromMilliseconds(1));
   EXPECT_FALSE(entry_->ShouldRejectRequest(request_));
 
-  scoped_ptr<base::HistogramSamples> samples(
-      histogram_recorder_->GetHistogramSamplesSinceCreation(
-          kRequestThrottledHistogramName));
-  ASSERT_EQ(2, samples->GetCount(0));
-  ASSERT_EQ(0, samples->GetCount(1));
+  CalculateHistogramDeltas();
+  ASSERT_EQ(2, samples_["Throttling.RequestThrottled"]->GetCount(0));
+  ASSERT_EQ(0, samples_["Throttling.RequestThrottled"]->GetCount(1));
 }
 
 TEST_F(URLRequestThrottlerEntryTest, InterfaceUpdateFailure) {