[Sync] Rework SharedValue<T> into Immutable<T>

chrome/browser/sync/syncable/transaction_observer.h

 // Copyright (c) 2011 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_SYNC_SYNCABLE_TRANSACTION_OBSERVER_H_
 #define CHROME_BROWSER_SYNC_SYNCABLE_TRANSACTION_OBSERVER_H_
 #pragma once
 
 #include "chrome/browser/sync/syncable/model_type.h"
 #include "chrome/browser/sync/syncable/syncable.h"
 
 namespace tracked_objects {
 class Location;
 }  // namespace tracked_objects
 
 namespace syncable {
 
 class TransactionObserver {
  public:
   virtual void OnTransactionStart(
       const tracked_objects::Location& location,
       const WriterTag& writer) = 0;
   virtual void OnTransactionMutate(
       const tracked_objects::Location& location,
       const WriterTag& writer,
-      const SharedEntryKernelMutationMap& mutations,
+      const ImmutableEntryKernelMutationMap& mutations,
       const ModelTypeBitSet& models_with_changes) = 0;
   virtual void OnTransactionEnd(
       const tracked_objects::Location& location,
       const WriterTag& writer) = 0;
  protected:
   virtual ~TransactionObserver() {}
 };
 
 }  // namespace syncable
 
 #endif  // CHROME_BROWSER_SYNC_SYNCABLE_TRANSACTION_OBSERVER_H_