Remove dependency of PrefSyncableService on Profile.

chrome/browser/prefs/pref_model_associator_client.h

+// 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_PREFS_PREF_MODEL_ASSOCIATOR_CLIENT_H_
+#define CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_CLIENT_H_
+
+#include <map>
+#include <string>
+
+#include "base/macros.h"
+
+// Type of preference that can have special treatment during synchronisation.
+enum PrefModelAssociatorPreferenceType {

[gab, 2015/09/10 14:15:09]

Make this an enum class (or move it inside the PrefModelAssociatorClient's
class) and then make the value's names much shorter.

+  PREF_MODEL_PREFERENCE_TYPE_LIST,
+  PREF_MODEL_PREFERENCE_TYPE_DICT,
+};
+
+// This class stores preferences names that should have local value merged
+// with server value during synchronisation instead of being replaced.
+class PrefModelAssociatorClient {
+ public:
+  PrefModelAssociatorClient();
+  virtual ~PrefModelAssociatorClient();
+
+  // Register a preference that should be merged with server value during
+  // synchronisation instead of being merged.

[gab, 2015/09/10 14:15:09]

"Should be merged instead of being merged"..? Feels like this comment is missing
something?

+  void RegisterPreference(const std::string& pref_name,

[gab, 2015/09/10 14:15:09]

Pref registration is already a separate concept in prefs and using it here will
be confusing to readers familiar with pref code.

Suggest something more specific like MarkMergedPreference()?

+                          PrefModelAssociatorPreferenceType pref_type);
+
+  // Returns whether the preference named |pref_name| should be merged with
+  // service value during synchronisation instead of being merged, and its

[gab, 2015/09/10 14:15:09]

Once again I don't see what you mean by "instead of being merged" here?

[gab, 2015/09/10 14:15:09]

s/, and/as well as/

[gab, 2015/09/10 14:15:09]

s/service/server/

+  // type via |pref_type| (must not be null).
+  bool IsPreferenceMerged(const std::string& pref_name,
+                          PrefModelAssociatorPreferenceType* pref_type);
+
+ private:
+  std::map<std::string, PrefModelAssociatorPreferenceType> pref_registry_;

[gab, 2015/09/10 14:15:09]

PrefRegistry is already a separate concept in prefs and using it here will be
confusing to readers familiar with pref code.

Suggest a more specific name like |merged_preferences_types_|?

+
+  DISALLOW_COPY_AND_ASSIGN(PrefModelAssociatorClient);
+};
+
+#endif  // CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_CLIENT_H_