Revert of Keep track of which attachments are referenced by which sync entries.

sync/syncable/directory.h

Index: sync/syncable/directory.h
diff --git a/sync/syncable/directory.h b/sync/syncable/directory.h
index 5d26bbdbac34ab006f3c1cfa4dfb7b22918d27d4..fdac9b4afe7ad9cd490beca7206b9f271505775b 100644
--- a/sync/syncable/directory.h
+++ b/sync/syncable/directory.h
@@ -47,9 +47,6 @@
   FULL_DB_VERIFICATION = 2 // Check every entry.  This can be expensive.
 };
 
-// Directory stores and manages EntryKernels.
-//
-// This class is tightly coupled to several other classes (see friends).
 class SYNC_EXPORT Directory {
   friend class BaseTransaction;
   friend class Entry;
@@ -83,9 +80,6 @@
   typedef base::hash_map<int64, EntryKernel*> MetahandlesMap;
   typedef base::hash_map<std::string, EntryKernel*> IdsMap;
   typedef base::hash_map<std::string, EntryKernel*> TagsMap;
-  typedef std::string AttachmentIdUniqueId;
-  typedef base::hash_map<AttachmentIdUniqueId, MetahandleSet>
-      IndexByAttachmentId;
 
   static const base::FilePath::CharType kSyncDatabaseFilename[];
 
@@ -389,14 +383,6 @@
   // WARNING! This can be slow, as it iterates over all entries for a type.
   bool ResetVersionsForType(BaseWriteTransaction* trans, ModelType type);
 
-  // Returns true iff the attachment identified by |attachment_id_proto| is
-  // linked to an entry.
-  //
-  // An attachment linked to a deleted entry is still considered linked if the
-  // entry hasn't yet been purged.
-  bool IsAttachmentLinked(
-      const sync_pb::AttachmentIdProto& attachment_id_proto) const;
-
  protected:  // for friends, mainly used by Entry constructors
   virtual EntryKernel* GetEntryByHandle(int64 handle);
   virtual EntryKernel* GetEntryByHandle(int64 metahandle,
@@ -408,11 +394,6 @@
                  const Id& new_id);
   bool ReindexParentId(BaseWriteTransaction* trans, EntryKernel* const entry,
                        const Id& new_parent_id);
-  // Update the attachment index for |metahandle| removing it from the index
-  // under |old_metadata| entries and add it under |new_metadata| entries.
-  void UpdateAttachmentIndex(const int64 metahandle,
-                             const sync_pb::AttachmentMetadata& old_metadata,
-                             const sync_pb::AttachmentMetadata& new_metadata);
   void ClearDirtyMetahandles();
 
   DirOpenResult OpenImpl(
@@ -470,17 +451,6 @@
     // within parent.  Protected by the ScopedKernelLock.
     ParentChildIndex parent_child_index;
 
-    // This index keeps track of which metahandles refer to a given attachment.
-    // Think of it as the inverse of EntryKernel's AttachmentMetadata Records.
-    //
-    // Because entries can be undeleted (e.g. PutIsDel(false)), entries should
-    // not removed from the index until they are actually deleted from memory.
-    //
-    // All access should go through IsAttachmentLinked,
-    // RemoveFromAttachmentIndex, AddToAttachmentIndex, and
-    // UpdateAttachmentIndex methods to avoid iterator invalidation errors.
-    IndexByAttachmentId index_by_attachment_id;
-
     // 3 in-memory indices on bits used extremely frequently by the syncer.
     // |unapplied_update_metahandles| is keyed by the server model type.
     MetahandleSet unapplied_update_metahandles[MODEL_TYPE_COUNT];
@@ -573,19 +543,7 @@
   void UnapplyEntry(EntryKernel* entry);
   void DeleteEntry(bool save_to_journal,
                    EntryKernel* entry,
-                   EntryKernelSet* entries_to_journal,
-                   const ScopedKernelLock& lock);
-
-  // Remove each of |metahandle|'s attachment ids from index_by_attachment_id.
-  void RemoveFromAttachmentIndex(
-      const int64 metahandle,
-      const sync_pb::AttachmentMetadata& attachment_metadata,
-      const ScopedKernelLock& lock);
-  // Add each of |metahandle|'s attachment ids to the index_by_attachment_id.
-  void AddToAttachmentIndex(
-      const int64 metahandle,
-      const sync_pb::AttachmentMetadata& attachment_metadata,
-      const ScopedKernelLock& lock);
+                   EntryKernelSet* entries_to_journal);
 
   Kernel* kernel_;