Revert 112815 - [Sync] Make syncer commands avoid posting tasks on threads with no work to do

chrome/browser/sync/syncable/syncable.h

Index: chrome/browser/sync/syncable/syncable.h
===================================================================
--- chrome/browser/sync/syncable/syncable.h	(revision 112854)
+++ chrome/browser/sync/syncable/syncable.h	(working copy)
@@ -371,8 +371,6 @@
     return id_fields[field - ID_FIELDS_BEGIN];
   }
 
-  syncable::ModelType GetServerModelType() const;
-
   // Does a case in-sensitive search for a given string, which must be
   // lower case.
   bool ContainsString(const std::string& lowercase_query) const;
@@ -489,6 +487,9 @@
   EntryKernel* kernel_;
 
  private:
+  // Like GetServerModelType() but without the DCHECKs.
+  ModelType GetServerModelTypeHelper() const;
+
   DISALLOW_COPY_AND_ASSIGN(Entry);
 };
 
@@ -968,17 +969,9 @@
   void GetUnsyncedMetaHandles(BaseTransaction* trans,
                               UnsyncedMetaHandles* result);
 
-  // Returns all server types with unapplied updates.  A subset of
-  // those types can then be passed into
-  // GetUnappliedUpdateMetaHandles() below.
-  syncable::ModelTypeBitSet GetServerTypesWithUnappliedUpdates(
-      BaseTransaction* trans) const;
-
-  // Get all the metahandles for unapplied updates for a given set of
-  // server types.
+  // Get all the metahandles for unapplied updates
   typedef std::vector<int64> UnappliedUpdateMetaHandles;
   void GetUnappliedUpdateMetaHandles(BaseTransaction* trans,
-                                     syncable::ModelTypeBitSet server_types,
                                      UnappliedUpdateMetaHandles* result);
 
   // Checks tree metadata consistency.
@@ -1110,8 +1103,7 @@
     EntryKernel needle;
 
     // 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];
+    MetahandleSet* const unapplied_update_metahandles;
     MetahandleSet* const unsynced_metahandles;
     // Contains metahandles that are most likely dirty (though not
     // necessarily).  Dirtyness is confirmed in TakeSnapshotForSaveChanges().