[Sync] Implement support for updating storage key for new entities

components/sync/model/fake_model_type_sync_bridge.h

Index: components/sync/model/fake_model_type_sync_bridge.h
diff --git a/components/sync/model/fake_model_type_sync_bridge.h b/components/sync/model/fake_model_type_sync_bridge.h
index f71b347296c0ef41dd523ccdfe8ae4be8f23772b..b6e1226abbfa36cbb059aeb41540b12c9c75eccc 100644
--- a/components/sync/model/fake_model_type_sync_bridge.h
+++ b/components/sync/model/fake_model_type_sync_bridge.h
@@ -106,7 +106,10 @@ class FakeModelTypeSyncBridge : public ModelTypeSyncBridge {
   std::unique_ptr<MetadataChangeList> CreateMetadataChangeList() override;
   base::Optional<ModelError> MergeSyncData(
       std::unique_ptr<MetadataChangeList> metadata_change_list,
-      EntityDataMap entity_data_map) override;
+      EntityChangeList entity_data) override;
+  base::Optional<ModelError> MergeSyncData(
+      std::unique_ptr<MetadataChangeList> metadata_change_list,
+      EntityDataMap entity_data) override;
   base::Optional<ModelError> ApplySyncChanges(
       std::unique_ptr<MetadataChangeList> metadata_change_list,
       EntityChangeList entity_changes) override;
@@ -114,6 +117,8 @@ class FakeModelTypeSyncBridge : public ModelTypeSyncBridge {
   void GetAllData(DataCallback callback) override;
   std::string GetClientTag(const EntityData& entity_data) override;
   std::string GetStorageKey(const EntityData& entity_data) override;
+  bool SupportsGetStorageKey() const override;
+  void SetSupportsGetStorageKey(bool supports_get_storage_key);
   ConflictResolution ResolveConflict(
       const EntityData& local_data,
       const EntityData& remote_data) const override;
@@ -140,11 +145,18 @@ class FakeModelTypeSyncBridge : public ModelTypeSyncBridge {
   // Applies |change_list| to the metadata store.
   void ApplyMetadataChangeList(std::unique_ptr<MetadataChangeList> change_list);
 
+  std::string GetStorageKeyImpl(const EntityData& entity_data);
+
   // The conflict resolution to use for calls to ResolveConflict.
   std::unique_ptr<ConflictResolution> conflict_resolution_;
 
   // Whether an error should be produced on the next bridge call.
   bool error_next_ = false;
+
+  // Whether the bridge supports call to GetStorageKey. If it doesn't bridge is
+  // responsible for calling UpdateStorageKey when processing new entities in
+  // MergeSyncData/ApplySyncChanges.
+  bool supports_get_storage_key_ = true;
 };
 
 }  // namespace syncer