Revert of Move base/prefs to components/prefs

base/prefs/pref_store.h

Index: base/prefs/pref_store.h
diff --git a/base/prefs/pref_store.h b/base/prefs/pref_store.h
index c1c658396ef0033f11bc8aa340af687d10c39a31..f95c8c42cb5893fb26a4f6177350fdcf9af4ed5b 100644
--- a/base/prefs/pref_store.h
+++ b/base/prefs/pref_store.h
@@ -2,6 +2,62 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// TODO(brettw) remove this forwarding header when prefs is completely moved to
-// components.
-#include "components/prefs/pref_store.h"
+#ifndef BASE_PREFS_PREF_STORE_H_
+#define BASE_PREFS_PREF_STORE_H_
+
+#include <string>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/prefs/base_prefs_export.h"
+
+namespace base {
+class Value;
+}
+
+// This is an abstract interface for reading and writing from/to a persistent
+// preference store, used by PrefService. An implementation using a JSON file
+// can be found in JsonPrefStore, while an implementation without any backing
+// store for testing can be found in TestingPrefStore. Furthermore, there is
+// CommandLinePrefStore, which bridges command line options to preferences and
+// ConfigurationPolicyPrefStore, which is used for hooking up configuration
+// policy with the preference subsystem.
+class BASE_PREFS_EXPORT PrefStore : public base::RefCounted<PrefStore> {
+ public:
+  // Observer interface for monitoring PrefStore.
+  class BASE_PREFS_EXPORT Observer {
+   public:
+    // Called when the value for the given |key| in the store changes.
+    virtual void OnPrefValueChanged(const std::string& key) = 0;
+    // Notification about the PrefStore being fully initialized.
+    virtual void OnInitializationCompleted(bool succeeded) = 0;
+
+   protected:
+    virtual ~Observer() {}
+  };
+
+  PrefStore() {}
+
+  // Add and remove observers.
+  virtual void AddObserver(Observer* observer) {}
+  virtual void RemoveObserver(Observer* observer) {}
+  virtual bool HasObservers() const;
+
+  // Whether the store has completed all asynchronous initialization.
+  virtual bool IsInitializationComplete() const;
+
+  // Get the value for a given preference |key| and stores it in |*result|.
+  // |*result| is only modified if the return value is true and if |result|
+  // is not NULL. Ownership of the |*result| value remains with the PrefStore.
+  virtual bool GetValue(const std::string& key,
+                        const base::Value** result) const = 0;
+
+ protected:
+  friend class base::RefCounted<PrefStore>;
+  virtual ~PrefStore() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PrefStore);
+};
+
+#endif  // BASE_PREFS_PREF_STORE_H_