Separate storage for protected preferences into Protected Preferences file.

chrome/browser/prefs/tracked/segregated_pref_store.h

Index: chrome/browser/prefs/tracked/segregated_pref_store.h
diff --git a/chrome/browser/prefs/tracked/segregated_pref_store.h b/chrome/browser/prefs/tracked/segregated_pref_store.h
index b7bc6e9a8bfca7e8c6ade59d603e6c62bc1211e0..f2f701b20e1064c19145ab306cdd981bf1f45010 100644
--- a/chrome/browser/prefs/tracked/segregated_pref_store.h
+++ b/chrome/browser/prefs/tracked/segregated_pref_store.h
@@ -18,6 +18,16 @@
 // Provides a unified PersistentPrefStore implementation that splits its storage
 // and retrieval between two underlying PersistentPrefStore instances: a set of
 // preference names is used to partition the preferences.
+//
+// Combines properties of the two stores as follows:
+//   * The unified read error will be:
+//                           Selected Store Error
+//    Default Store Error | NO_ERROR      | NO_FILE       | other selected |
+//               NO_ERROR | NO_ERROR      | NO_ERROR      | other selected |
+//               NO_FILE  | NO_FILE       | NO_FILE       | NO_FILE        |
+//          other default | other default | other default | other default  |
+//   * The unified initialization success, initialization completion, and
+//     read-only state are the boolean OR of the underlying stores' properties.
 class SegregatedPrefStore : public PersistentPrefStore {
  public:
   // Creates an instance that delegates to |selected_pref_store| for the