Adding a previews object, PreviewsDataSavings

components/previews/previews_data_savings.h

+// Copyright 2016 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 CHROME_BROWSER_PREVIEWS_PREVIEWS_DATA_SAVINGS_H_
+#define CHROME_BROWSER_PREVIEWS_PREVIEWS_DATA_SAVINGS_H_
+
+#include <stdint.h>
+
+#include <string>
+
+#include "base/macros.h"
+#include "base/threading/thread_checker.h"
+
+namespace data_reduction_proxy {
+class DataSavingsRecorder;
+}
+
+namespace previews {
+
+// Provides an interface for previews to report data savings.
+class PreviewsDataSavings {
+ public:
+  // Embedder must guarantee that |data_savings_recorder| and
+  // |data_reduction_proxy_settings| outlive this instance.
+  PreviewsDataSavings(
+      data_reduction_proxy::DataSavingsRecorder* data_savings_recorder);
+  ~PreviewsDataSavings();
+
+  // Records the amount of data used by the preview, and the amount of data
+  // that would have been used if the original page had been loaded instead of
+  // the preview. |fully_qualified_domain_name| is the full host name to
+  // attribute the data savings to (e.g., codereview.chromium.org).
+  void RecordDataSavings(const std::string& fully_qualified_domain_name,
+                         int64_t data_used,
+                         int64_t original_size);
+
+ private:
+  // Owned by the embedder, must be valid for the lifetime of |this|.
+  // Provides a method to record data savings.
+  data_reduction_proxy::DataSavingsRecorder* data_savings_recorder_;
+
+  // Enforce usage on the UI thread.
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(PreviewsDataSavings);
+};
+
+}  // namespace previews
+
+#endif  // CHROME_BROWSER_PREVIEWS_PREVIEWS_DATA_SAVINGS_H_