[Sync] Remove unneeded 'using syncer::' lines and 'syncer::' scopings

sync/internal_api/public/engine/model_safe_worker.h

Index: sync/internal_api/public/engine/model_safe_worker.h
diff --git a/sync/internal_api/public/engine/model_safe_worker.h b/sync/internal_api/public/engine/model_safe_worker.h
index 9f1c7020d9a7ceba46407f100ccc9e08060ed263..d67f4b6865ab497b81a10f0bf378a0f6eb5da1f5 100644
--- a/sync/internal_api/public/engine/model_safe_worker.h
+++ b/sync/internal_api/public/engine/model_safe_worker.h
@@ -68,11 +68,10 @@ class SYNC_EXPORT ModelSafeWorker
   friend class base::RefCountedThreadSafe<ModelSafeWorker>;
 };
 
-// A map that details which ModelSafeGroup each syncer::ModelType
+// A map that details which ModelSafeGroup each ModelType
 // belongs to.  Routing info can change in response to the user enabling /
 // disabling sync for certain types, as well as model association completions.
-typedef std::map<syncer::ModelType, ModelSafeGroup>
-    ModelSafeRoutingInfo;
+typedef std::map<ModelType, ModelSafeGroup> ModelSafeRoutingInfo;
 
 // Caller takes ownership of return value.
 base::DictionaryValue* ModelSafeRoutingInfoToValue(
@@ -83,15 +82,15 @@ SYNC_EXPORT std::string ModelSafeRoutingInfoToString(
 
 // Make a ModelTypePayloadMap for all the enabled types in a
 // ModelSafeRoutingInfo using a default payload.
-syncer::ModelTypePayloadMap ModelSafeRoutingInfoToPayloadMap(
+ModelTypePayloadMap ModelSafeRoutingInfoToPayloadMap(
     const ModelSafeRoutingInfo& routes,
     const std::string& payload);
 
-SYNC_EXPORT syncer::ModelTypeSet GetRoutingInfoTypes(
+SYNC_EXPORT ModelTypeSet GetRoutingInfoTypes(
     const ModelSafeRoutingInfo& routing_info);
 
 SYNC_EXPORT ModelSafeGroup GetGroupForModelType(
-    const syncer::ModelType type,
+    const ModelType type,
     const ModelSafeRoutingInfo& routes);
 
 }  // namespace syncer