Add DataReductionProxyExperimentsStats and UMA for measuring potentially non-compressed bytes.

components/data_reduction_proxy/core/browser/data_reduction_proxy_experiments_stats.h

Index: components/data_reduction_proxy/core/browser/data_reduction_proxy_experiments_stats.h
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_experiments_stats.h b/components/data_reduction_proxy/core/browser/data_reduction_proxy_experiments_stats.h
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index 0000000000000000000000000000000000000000..1806d5167c39d4a2e3707a495c8f3424d6ddf006
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+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_experiments_stats.h
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+// Copyright 2015 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.
+
+#ifndef COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_REDUCTION_PROXY_EXPERIMENTS_STATS_H_
+#define COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_REDUCTION_PROXY_EXPERIMENTS_STATS_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "base/timer/timer.h"
+#include "components/data_reduction_proxy/core/browser/data_reduction_proxy_metrics.h"
+
+namespace base {
+class Time;
+}
+
+namespace data_reduction_proxy {
+
+class DataReductionProxyConfigRetrievalParams;
+
+typedef base::Callback<void(const std::string&, int64)> Int64ValueSetter;
+
+// Collects statistics specific to experiments of which a client may be part.
+// Any calls into this class should be as lightweight as possible such that if
+// no experiments are being performed, there should be minimal code being
+// executed.
+// Currently supported experiments are:
+// - Measuring potentially uncompressed bytes during simulated config retrieval.
+class DataReductionProxyExperimentsStats {
+ public:
+  DataReductionProxyExperimentsStats(const Int64ValueSetter& value_setter);
+  virtual ~DataReductionProxyExperimentsStats();
+
+  // Initializes |this| on the UI thread. If called, must be called prior to
+  // InitializeOnIOThread.
+  void InitializeOnUIThread(scoped_ptr<DataReductionProxyConfigRetrievalParams>
+                                config_retrieval_params);
+
+  // Initializes |this| on the IO thread.
+  void InitializeOnIOThread();
+
+  // Collect received bytes for the experiment.
+  void RecordBytes(const base::Time& request_time,
+                   DataReductionProxyRequestType request_type,
+                   int64 received_content_length,
+                   int64 original_content_length);
+
+ private:
+  // Updates the simulated expiration of the Data Reduction Proxy configuration
+  // if |config_retrieval_| is set.
+  void UpdateSimulatedConfig();
+
+  // Allows an experiment to persist data to preferences.
+  Int64ValueSetter value_setter_;
+
+  // Enables measuring of potentially uncompressed bytes during a simulated Data
+  // Reduction Proxy configuration retrieval.
+  scoped_ptr<DataReductionProxyConfigRetrievalParams> config_retrieval_params_;
+
+  // If set, periodically updates the simulated expiration of the Data Reduction
+  // Proxy configuration.
+  base::RepeatingTimer<DataReductionProxyExperimentsStats> config_refresh_time_;
+
+  // Enforce initialization order.
+  bool initialized_;
+
+  // Enforce usage on the IO thread.
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(DataReductionProxyExperimentsStats);
+};
+
+}  // namespace data_reduction_proxy
+
+#endif  // COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_REDUCTION_PROXY_EXPERIMENTS_STATS_H_