Refactor sync-specific parts out of SyncNotifier/SyncNotifierObserver

sync/internal_api/public/base/model_type_payload_map.cc

Index: sync/internal_api/public/base/model_type_payload_map.cc
diff --git a/sync/internal_api/public/base/model_type_payload_map.cc b/sync/internal_api/public/base/model_type_payload_map.cc
index 04222ee30266282f4e42d36824c32793ac85501d..af9c503e4088dfc831a1cccb4b343c05dbc36429 100644
--- a/sync/internal_api/public/base/model_type_payload_map.cc
+++ b/sync/internal_api/public/base/model_type_payload_map.cc
@@ -10,9 +10,42 @@
 #include "base/json/json_writer.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/values.h"
+#include "google/cacheinvalidation/include/types.h"
+#include "sync/notifier/invalidation_util.h"
 
 namespace syncer {
 
+ModelTypePayloadMap ObjectIdPayloadMapToModelTypePayloadMap(
+    const ObjectIdPayloadMap& id_payloads) {
+  ModelTypePayloadMap types_with_payloads;
+  for (ObjectIdPayloadMap::const_iterator it = id_payloads.begin();
+       it != id_payloads.end(); ++it) {
+    ModelType model_type;
+    if (!syncer::ObjectIdToRealModelType(it->first, &model_type)) {
+      DLOG(WARNING) << "Invalid object ID: "
+                    << syncer::ObjectIdToString(it->first);
+      continue;
+    }
+    types_with_payloads[model_type] = it->second;
+  }
+  return types_with_payloads;
+}
+
+syncer::ObjectIdPayloadMap ModelTypePayloadMapToObjectIdPayloadMap(
+    const ModelTypePayloadMap& type_payloads) {
+  ObjectIdPayloadMap id_payloads;
+  for (ModelTypePayloadMap::const_iterator it = type_payloads.begin();
+       it != type_payloads.end(); ++it) {
+    invalidation::ObjectId id;
+    if (!RealModelTypeToObjectId(it->first, &id)) {
+      DLOG(WARNING) << "Invalid model type " << it->first;
+      continue;
+    }
+    id_payloads[id] = it->second;
+  }
+  return id_payloads;
+}
+
 ModelTypePayloadMap ModelTypePayloadMapFromEnumSet(
     syncer::ModelTypeSet types,
     const std::string& payload) {