Upstream oodles of Chrome for Android code into Chromium.

chrome/browser/android/history_report/usage_reports_buffer_backend.h

Index: chrome/browser/android/history_report/usage_reports_buffer_backend.h
diff --git a/chrome/browser/android/history_report/usage_reports_buffer_backend.h b/chrome/browser/android/history_report/usage_reports_buffer_backend.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 CHROME_BROWSER_ANDROID_HISTORY_REPORT_USAGE_REPORTS_BUFFER_BACKEND_H_
+#define CHROME_BROWSER_ANDROID_HISTORY_REPORT_USAGE_REPORTS_BUFFER_BACKEND_H_
+
+#include <string>
+#include <vector>
+
+#include "base/files/file_path.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace base {
+class FilePath;
+}  // namespace base
+
+namespace leveldb {
+class DB;
+}  // namespace leveldb
+
+namespace history_report {
+
+class UsageReport;
+
+// Stores usage reports which will be sent for history reporting in batches.
+class UsageReportsBufferBackend {
+ public:
+  explicit UsageReportsBufferBackend(const base::FilePath& dir);
+
+  ~UsageReportsBufferBackend();
+
+  // Creates and initializes the internal data structures.
+  bool Init();
+
+  void AddVisit(const std::string& id, int64 timestamp_ms, bool typed_visit);
+
+  // Returns a set of up to |amount| usage reports.
+  scoped_ptr<std::vector<UsageReport> > GetUsageReportsBatch(int amount);
+
+  void Remove(const std::vector<std::string>& reports);
+
+  // Clears the buffer by removing all its usage reports.
+  void Clear();
+
+  // Dumps internal state to string. For debuging.
+  std::string Dump();
+
+ private:
+  // NULL until Init method is called.
+  scoped_ptr<leveldb::DB> db_;
+  base::FilePath db_file_name_;
+
+  DISALLOW_COPY_AND_ASSIGN(UsageReportsBufferBackend);
+};
+
+}  // namespace history_report
+
+#endif  // CHROME_BROWSER_ANDROID_HISTORY_REPORT_USAGE_REPORTS_BUFFER_BACKEND_H_