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

chrome/browser/sync/syncable/syncable.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_SYNCABLE_H_
 #define CHROME_BROWSER_SYNC_SYNCABLE_SYNCABLE_H_
 #pragma once
 
 #include <algorithm>
 #include <bitset>
@@ skipping 14 matching lines @@
 #include "base/synchronization/lock.h"
 #include "base/time.h"
 #include "base/tracked.h"
 #include "chrome/browser/sync/protocol/sync.pb.h"
 #include "chrome/browser/sync/syncable/blob.h"
 #include "chrome/browser/sync/syncable/dir_open_result.h"
 #include "chrome/browser/sync/syncable/directory_event.h"
 #include "chrome/browser/sync/syncable/syncable_id.h"
 #include "chrome/browser/sync/syncable/model_type.h"
 #include "chrome/browser/sync/util/dbgq.h"
-#include "chrome/browser/sync/util/shared_value.h"
+#include "chrome/browser/sync/util/immutable.h"
 
 struct PurgeInfo;
 
 namespace base {
 class DictionaryValue;
 class ListValue;
 }
 
 namespace sync_api {
 class ReadTransaction;
@@ skipping 510 matching lines @@
     return a.ref(META_HANDLE) < b.ref(META_HANDLE);
   }
 };
 typedef std::set<EntryKernel, EntryKernelLessByMetaHandle> EntryKernelSet;
 
 struct EntryKernelMutation {
   EntryKernel original, mutated;
 };
 typedef std::map<int64, EntryKernelMutation> EntryKernelMutationMap;
 
-// A thread-safe wrapper around an immutable mutation map.  Used for
-// passing around mutation maps without incurring lots of copies.
-class SharedEntryKernelMutationMap {
- public:
-  SharedEntryKernelMutationMap();
-  // Takes over the data in |mutations|, leaving |mutations| empty.
-  explicit SharedEntryKernelMutationMap(EntryKernelMutationMap* mutations);
-
-  ~SharedEntryKernelMutationMap();
-
-  const EntryKernelMutationMap& Get() const;
-
- private:
-  struct MutationMapTraits {
-    static void Swap(EntryKernelMutationMap* mutations1,
-                     EntryKernelMutationMap* mutations2);
-  };
-
-  typedef browser_sync::SharedValue<EntryKernelMutationMap, MutationMapTraits>
-      SharedMutationMap;
-
-  scoped_refptr<const SharedMutationMap> mutations_;
-};
+typedef browser_sync::Immutable<EntryKernelMutationMap>
+    ImmutableEntryKernelMutationMap;
 
 // Caller owns the return value.
 base::ListValue* EntryKernelMutationMapToValue(
     const EntryKernelMutationMap& mutations);
 
 // How syncable indices & Indexers work.
 //
 // The syncable Directory maintains several indices on the Entries it tracks.
 // The indices follow a common pattern:
 //   (a) The index allows efficient lookup of an Entry* with particular
@@ skipping 582 matching lines @@
 
   void SaveOriginal(const EntryKernel* entry);
 
  protected:
   // Overridden by tests.
   virtual void NotifyTransactionComplete(
       ModelTypeBitSet models_with_changes);
 
  private:
   // Clears |mutations_|.
-  SharedEntryKernelMutationMap RecordMutations();
+  ImmutableEntryKernelMutationMap RecordMutations();
 
-  void UnlockAndNotify(const SharedEntryKernelMutationMap& mutations);
+  void UnlockAndNotify(const ImmutableEntryKernelMutationMap& mutations);
 
   ModelTypeBitSet NotifyTransactionChangingAndEnding(
-      const SharedEntryKernelMutationMap& mutations);
+      const ImmutableEntryKernelMutationMap& mutations);
 
   // Only the original fields are filled in until |RecordMutations()|.
   // We use a mutation map instead of a kernel set to avoid copying.
   EntryKernelMutationMap mutations_;
 
   DISALLOW_COPY_AND_ASSIGN(WriteTransaction);
 };
 
 bool IsLegalNewParent(BaseTransaction* trans, const Id& id, const Id& parentid);
 
 int64 Now();
 
 // This function sets only the flags needed to get this entry to sync.
 void MarkForSyncing(syncable::MutableEntry* e);
 
 // This is not a reset.  It just sets the numeric fields which are not
 // initialized by the constructor to zero.
 void ZeroFields(EntryKernel* entry, int first_field);
 
 }  // namespace syncable
 
 std::ostream& operator <<(std::ostream&, const syncable::Blob&);
 
 #endif  // CHROME_BROWSER_SYNC_SYNCABLE_SYNCABLE_H_