Index: base/test/statistics_delta_reader.cc |
diff --git a/base/test/statistics_delta_reader.cc b/base/test/statistics_delta_reader.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..9e77b8b733461e4194375fabbb49a8c13ef590df |
--- /dev/null |
+++ b/base/test/statistics_delta_reader.cc |
@@ -0,0 +1,41 @@ |
+// Copyright 2014 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 "base/test/statistics_delta_reader.h" |
+ |
+#include "base/metrics/histogram.h" |
+#include "base/metrics/statistics_recorder.h" |
+#include "base/stl_util.h" |
+ |
+namespace base { |
+ |
+StatisticsDeltaReader::StatisticsDeltaReader() { |
+ // Record any histogram data that exists when the object is created so it can |
+ // be subtracted later. |
+ StatisticsRecorder::Histograms histograms; |
+ StatisticsRecorder::GetSnapshot(std::string(), &histograms); |
+ for (size_t i = 0; i < histograms.size(); ++i) { |
+ original_samples_[histograms[i]->histogram_name()] = |
+ histograms[i]->SnapshotSamples().release(); |
+ } |
+} |
+ |
+StatisticsDeltaReader::~StatisticsDeltaReader() { |
+ STLDeleteValues(&original_samples_); |
+} |
+ |
+scoped_ptr<HistogramSamples> |
+ StatisticsDeltaReader::GetHistogramSamplesSinceCreation( |
+ const std::string& histogram_name) { |
+ HistogramBase* histogram = StatisticsRecorder::FindHistogram(histogram_name); |
+ if (!histogram) |
+ return scoped_ptr<HistogramSamples>(); |
+ scoped_ptr<HistogramSamples> named_samples(histogram->SnapshotSamples()); |
+ HistogramSamples* named_original_samples = original_samples_[histogram_name]; |
+ if (named_original_samples) |
+ named_samples->Subtract(*named_original_samples); |
+ return named_samples.Pass(); |
+} |
+ |
+} // namespace base |