Revert of Move base/prefs to components/prefs

base/prefs/pref_registry.h

Index: base/prefs/pref_registry.h
diff --git a/base/prefs/pref_registry.h b/base/prefs/pref_registry.h
index 94126d1ae1175bf68ef7abdec8da452e8f4b9b4f..7e141d8b7e5d0f5eaf6c4a8147aa9df2a2422190 100644
--- a/base/prefs/pref_registry.h
+++ b/base/prefs/pref_registry.h
@@ -2,6 +2,88 @@
 // 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_registry.h"
+#ifndef BASE_PREFS_PREF_REGISTRY_H_
+#define BASE_PREFS_PREF_REGISTRY_H_
+
+#include <stdint.h>
+
+#include "base/containers/hash_tables.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/prefs/base_prefs_export.h"
+#include "base/prefs/pref_value_map.h"
+
+namespace base {
+class Value;
+}
+
+class DefaultPrefStore;
+class PrefStore;
+
+// Preferences need to be registered with a type and default value
+// before they are used.
+//
+// The way you use a PrefRegistry is that you register all required
+// preferences on it (via one of its subclasses), then pass it as a
+// construction parameter to PrefService.
+//
+// Currently, registrations after constructing the PrefService will
+// also work, but this is being deprecated.
+class BASE_PREFS_EXPORT PrefRegistry : public base::RefCounted<PrefRegistry> {
+ public:
+  // Registration flags that can be specified which impact how the pref will
+  // behave or be stored. This will be passed in a bitmask when the pref is
+  // registered. Subclasses of PrefRegistry can specify their own flags. Care
+  // must be taken to ensure none of these overlap with the flags below.
+  enum PrefRegistrationFlags : uint32_t {
+    // No flags are specified.
+    NO_REGISTRATION_FLAGS = 0,
+
+    // The first 8 bits are reserved for subclasses of PrefRegistry to use.
+
+    // This marks the pref as "lossy". There is no strict time guarantee on when
+    // a lossy pref will be persisted to permanent storage when it is modified.
+    LOSSY_PREF = 1 << 8,
+  };
+
+  typedef PrefValueMap::const_iterator const_iterator;
+  typedef base::hash_map<std::string, uint32_t> PrefRegistrationFlagsMap;
+
+  PrefRegistry();
+
+  // Retrieve the set of registration flags for the given preference. The return
+  // value is a bitmask of PrefRegistrationFlags.
+  uint32_t GetRegistrationFlags(const std::string& pref_name) const;
+
+  // Gets the registered defaults.
+  scoped_refptr<PrefStore> defaults();
+
+  // Allows iteration over defaults.
+  const_iterator begin() const;
+  const_iterator end() const;
+
+  // Changes the default value for a preference. Takes ownership of |value|.
+  //
+  // |pref_name| must be a previously registered preference.
+  void SetDefaultPrefValue(const std::string& pref_name, base::Value* value);
+
+ protected:
+  friend class base::RefCounted<PrefRegistry>;
+  virtual ~PrefRegistry();
+
+  // Used by subclasses to register a default value and registration flags for
+  // a preference. |flags| is a bitmask of |PrefRegistrationFlags|.
+  void RegisterPreference(const std::string& path,
+                          base::Value* default_value,
+                          uint32_t flags);
+
+  scoped_refptr<DefaultPrefStore> defaults_;
+
+  // A map of pref name to a bitmask of PrefRegistrationFlags.
+  PrefRegistrationFlagsMap registration_flags_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PrefRegistry);
+};
+
+#endif  // BASE_PREFS_PREF_REGISTRY_H_