sync: Introduce ModelTypeRegistry and helpers

sync/engine/syncer_unittest.cc

Index: sync/engine/syncer_unittest.cc
diff --git a/sync/engine/syncer_unittest.cc b/sync/engine/syncer_unittest.cc
index 19aff7c3b115dd63a34d50cfb9bb53e03360d0f5..797d1748155b2f343a02f77e1bae5a3f1b0aed56 100644
--- a/sync/engine/syncer_unittest.cc
+++ b/sync/engine/syncer_unittest.cc
@@ -225,15 +225,18 @@ class SyncerTest : public testing::Test,
     GetModelSafeRoutingInfo(&routing_info);
     GetWorkers(&workers);
 
+    model_type_registry_.reset(new ModelTypeRegistry(workers, directory()));
+
     context_.reset(
         new SyncSessionContext(
-            mock_server_.get(), directory(), workers,
+            mock_server_.get(), directory(),
             extensions_activity_,
             listeners, debug_info_getter_.get(), &traffic_recorder_,
+            model_type_registry_.get(),
             true,  // enable keystore encryption
             false,  // force enable pre-commit GU avoidance experiment
             "fake_invalidator_client_id"));
-    context_->set_routing_info(routing_info);
+    context_->SetRoutingInfo(routing_info);
     syncer_ = new Syncer(&cancelation_signal_);
 
     syncable::ReadTransaction trans(FROM_HERE, directory());
@@ -442,7 +445,7 @@ class SyncerTest : public testing::Test,
     GetModelSafeRoutingInfo(&routing_info);
 
     if (context_) {
-      context_->set_routing_info(routing_info);
+      context_->SetRoutingInfo(routing_info);
     }
 
     mock_server_->ExpectGetUpdatesRequestTypes(enabled_datatypes_);
@@ -455,7 +458,7 @@ class SyncerTest : public testing::Test,
     GetModelSafeRoutingInfo(&routing_info);
 
     if (context_) {
-      context_->set_routing_info(routing_info);
+      context_->SetRoutingInfo(routing_info);
     }
 
     mock_server_->ExpectGetUpdatesRequestTypes(enabled_datatypes_);
@@ -498,6 +501,7 @@ class SyncerTest : public testing::Test,
   Syncer* syncer_;
 
   scoped_ptr<SyncSession> session_;
+  scoped_ptr<ModelTypeRegistry> model_type_registry_;
   scoped_ptr<SyncSessionContext> context_;
   bool saw_syncer_event_;
   base::TimeDelta last_short_poll_interval_received_;