FYI: Remove PerModelSafeGroupState + move ConflictResolution

sync/engine/apply_updates_command.cc

Index: sync/engine/apply_updates_command.cc
diff --git a/sync/engine/apply_updates_command.cc b/sync/engine/apply_updates_command.cc
index 7d4e72ec9290d063692d741e6a1fd037c1e40b52..ace48c76e2c22c1c27f8a667eea823ada40d5a2a 100644
--- a/sync/engine/apply_updates_command.cc
+++ b/sync/engine/apply_updates_command.cc
@@ -5,6 +5,7 @@
 #include "sync/engine/apply_updates_command.h"
 
 #include "base/location.h"
+#include "sync/engine/conflict_resolver.cc"
 #include "sync/engine/update_applicator.h"
 #include "sync/sessions/sync_session.h"
 #include "sync/syncable/directory.h"
@@ -65,15 +66,37 @@ SyncerError ApplyUpdatesCommand::ModelChangingExecuteImpl(
   dir->GetUnappliedUpdateMetaHandles(
       &trans, server_type_restriction, &handles);
 
+  // First set of update application passes.
+  std::set<syncable::Id> simple_conflict_ids;
   UpdateApplicator applicator(
-      session->context()->resolver(),
       dir->GetCryptographer(&trans),
-      handles.begin(), handles.end(), session->routing_info(),
+      session->routing_info(),
       session->status_controller().group_restriction());
-  while (applicator.AttemptOneApplication(&trans)) {}
-  applicator.SaveProgressIntoSessionState(
-      session->mutable_status_controller()->mutable_conflict_progress(),
-      session->mutable_status_controller()->mutable_update_progress());
+  applicator.AttemptApplications(&trans, handles,
+                                 &simple_conflict_ids /* out param */);
+
+  // Resolve all simple conflicts.
+  ConflictResolver resolver;
+  resolver.ResolveConflicts(&trans,
+                            dir->GetCryptographer(&trans),
+                            simple_conflict_ids,
+                            session->mutable_status_controller());
+
+  // Conflict resolution may have cleared the way for more applications.
+  // FIXME: this will cause us to double-count encryption and hierarchy
+  // conflicts.
+  handles.clear();
+  simple_conflict_ids.clear();
+  dir->GetUnappliedUpdateMetaHandles(
+      &trans, server_type_restriction, &handles);
+  applicator.AttemptApplications(&trans, handles,
+                                 &simple_conflict_ids /* out param */);
+
+  // FIXME: This may not be correct.  We ought to loop until no simple conflicts
+  // remain.
+  DCHECK(simple_conflict_ids.empty());
+
+  applicator.SaveStats(session->mutable_status_controller());
 
   // This might be the first time we've fully completed a sync cycle, for
   // some subset of the currently synced datatypes.