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diff --git a/extensions/browser/state_store.h b/extensions/browser/state_store.h
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+++ b/extensions/browser/state_store.h
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+// 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.
+
+#ifndef CHROME_BROWSER_EXTENSIONS_STATE_STORE_H_
+#define CHROME_BROWSER_EXTENSIONS_STATE_STORE_H_
+
+#include <set>
+#include <string>
+
+#include "base/files/file_path.h"
+#include "base/memory/weak_ptr.h"
+#include "base/scoped_observer.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+#include "extensions/browser/extension_registry_observer.h"
+#include "extensions/browser/value_store/value_store_frontend.h"
+
+namespace content {
+class BrowserContext;
+}
+
+namespace extensions {
+
+class ExtensionRegistry;
+
+// A storage area for per-extension state that needs to be persisted to disk.
+class StateStore : public base::SupportsWeakPtr<StateStore>,
+                   public ExtensionRegistryObserver,
+                   public content::NotificationObserver {
+ public:
+  typedef ValueStoreFrontend::ReadCallback ReadCallback;
+
+  // If |deferred_load| is true, we won't load the database until the first
+  // page has been loaded.
+  StateStore(content::BrowserContext* context,
+             const base::FilePath& db_path,
+             bool deferred_load);
+  // This variant is useful for testing (using a mock ValueStore).
+  StateStore(content::BrowserContext* context, scoped_ptr<ValueStore> store);
+  virtual ~StateStore();
+
+  // Register a key for removal upon extension install/uninstall. We remove
+  // for install to reset state when an extension upgrades.
+  void RegisterKey(const std::string& key);
+
+  // Get the value associated with the given extension and key, and pass
+  // it to |callback| asynchronously.
+  void GetExtensionValue(const std::string& extension_id,
+                         const std::string& key,
+                         ReadCallback callback);
+
+  // Sets a value for a given extension and key.
+  void SetExtensionValue(const std::string& extension_id,
+                         const std::string& key,
+                         scoped_ptr<base::Value> value);
+
+  // Removes a value for a given extension and key.
+  void RemoveExtensionValue(const std::string& extension_id,
+                            const std::string& key);
+
+  // Return whether or not the StateStore has initialized itself.
+  bool IsInitialized() const;
+
+ private:
+  class DelayedTaskQueue;
+
+  // content::NotificationObserver
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
+  void Init();
+
+  // Removes all keys registered for the given extension.
+  void RemoveKeysForExtension(const std::string& extension_id);
+
+  // ExtensionRegistryObserver implementation.
+  virtual void OnExtensionUninstalled(content::BrowserContext* browser_context,
+                                      const Extension* extension) OVERRIDE;
+  virtual void OnExtensionWillBeInstalled(
+      content::BrowserContext* browser_context,
+      const Extension* extension,
+      bool is_update,
+      bool from_ephemeral,
+      const std::string& old_name) OVERRIDE;
+
+  // Path to our database, on disk. Empty during testing.
+  base::FilePath db_path_;
+
+  // The store that holds our key/values.
+  ValueStoreFrontend store_;
+
+  // List of all known keys. They will be cleared for each extension when it is
+  // (un)installed.
+  std::set<std::string> registered_keys_;
+
+  // Keeps track of tasks we have delayed while starting up.
+  scoped_ptr<DelayedTaskQueue> task_queue_;
+
+  content::NotificationRegistrar registrar_;
+
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_STATE_STORE_H_