Revert 110555 - sync: Remove ModelNeutralExecuteImpl()

chrome/browser/sync/engine/model_changing_syncer_command.h

Index: chrome/browser/sync/engine/model_changing_syncer_command.h
===================================================================
--- chrome/browser/sync/engine/model_changing_syncer_command.h	(revision 110571)
+++ chrome/browser/sync/engine/model_changing_syncer_command.h	(working copy)
@@ -40,6 +40,14 @@
     return UnrecoverableErrorInfo();
   }
 
+  // Sometimes, a command has work to do that needs to touch global state
+  // belonging to multiple ModelSafeGroups, but in a way that is known to be
+  // safe.  This will be called once, prior to ModelChangingExecuteImpl,
+  // *without* a ModelSafeGroup restriction in place on the SyncSession.
+  // Returns true on success, false on failure.
+  // TODO(tim): Remove this (bug 36594).
+  virtual bool ModelNeutralExecuteImpl(sessions::SyncSession* session);
+
   // Abstract method to be implemented by subclasses to handle logic that
   // operates on the model.  This is invoked with a SyncSession ModelSafeGroup
   // restriction in place so that bits of state belonging to data types