LevelDB storage for data reduction proxy to store data usage stats.

components/data_reduction_proxy/core/browser/data_reduction_proxy_store.h

Index: components/data_reduction_proxy/core/browser/data_reduction_proxy_store.h
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_store.h b/components/data_reduction_proxy/core/browser/data_reduction_proxy_store.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_STORE_H_
+#define COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_REDUCTION_PROXY_STORE_H_
+
+#include <map>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+
+namespace data_reduction_proxy {
+
+// Interface for a permanent key value store used by the Data Reduction Proxy
+// component. Clients that do not want to support a permanent store can use
+// the |DummyDataReductionProxyStore| below, which provides no-op methods.
+class DataReductionProxyStore
+    : public base::RefCountedThreadSafe<DataReductionProxyStore> {
+ public:
+  enum Status { OK, NOT_FOUND, ERROR };
+
+  // Initializes the store on DB Thread.
+  virtual void InitializeOnDBThread() = 0;
+
+  // Gets the value from the store for the provided key.
+  virtual Status Get(const std::string& key, std::string& value) = 0;
+
+  // Persists the provided keys and values into the store.
+  virtual Status Put(const std::map<std::string, std::string>* map) = 0;
+
+ protected:
+  DataReductionProxyStore();
+  virtual ~DataReductionProxyStore() = 0;
+
+ private:
+  // Ref counted classes have private destructors to prevent accidental deletion
+  // of the object when there are still references to it.
+  friend class base::RefCountedThreadSafe<DataReductionProxyStore>;
+
+  DISALLOW_COPY_AND_ASSIGN(DataReductionProxyStore);
+};
+
+// Dummy implementation of |DataReductionProxyStore| with no-op methods.
+class DummyDataReductionProxyStore : public DataReductionProxyStore {
+ public:
+  DummyDataReductionProxyStore();
+  void InitializeOnDBThread() override;
+  DataReductionProxyStore::Status Get(const std::string& key,
+                                      std::string& value) override;
+  DataReductionProxyStore::Status Put(
+      const std::map<std::string, std::string>* map) override;
+
+ protected:
+  ~DummyDataReductionProxyStore() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DummyDataReductionProxyStore);
+};
+
+}  // namespace data_reduction_proxy
+
+#endif  // COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_REDUCTION_PROXY_STORE_H_