Revert 148792 - [Sync] Remove CleanupDisabledTypes command and move purge logic into SyncManager.

sync/sessions/sync_session_context.h

Index: sync/sessions/sync_session_context.h
===================================================================
--- sync/sessions/sync_session_context.h	(revision 148811)
+++ sync/sessions/sync_session_context.h	(working copy)
@@ -110,6 +110,14 @@
   }
   int32 max_commit_batch_size() const { return max_commit_batch_size_; }
 
+  const ModelSafeRoutingInfo& previous_session_routing_info() const {
+    return previous_session_routing_info_;
+  }
+
+  void set_previous_session_routing_info(const ModelSafeRoutingInfo& info) {
+    previous_session_routing_info_ = info;
+  }
+
   void NotifyListeners(const SyncEngineEvent& event) {
     FOR_EACH_OBSERVER(SyncEngineEventListener, listeners_,
                       OnSyncEngineEvent(event));
@@ -155,6 +163,10 @@
   // The server limits the number of items a client can commit in one batch.
   int max_commit_batch_size_;
 
+  // Some routing info history to help us clean up types that get disabled
+  // by the user.
+  ModelSafeRoutingInfo previous_session_routing_info_;
+
   ThrottledDataTypeTracker* throttled_data_type_tracker_;
 
   // We use this to get debug info to send to the server for debugging