[USS] Add function for update storage key for processor

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 07759719e5eecce3dc27a052bd0e4155bb04ef47..8b8753a0cffdd73f8ef227540055256738487d8d 100644
--- a/components/sync/model/fake_model_type_sync_bridge.h
+++ b/components/sync/model/fake_model_type_sync_bridge.h
@@ -125,21 +125,26 @@ class FakeModelTypeSyncBridge : public ModelTypeSyncBridge {
   // Sets an error that the next fallible call to the bridge will generate.
   void ErrorOnNextCall();
 
+  // It is intentionally very difficult to copy an EntityData, as in normal code
+  // we never want to. However, since we store the data as an EntityData for the
+  // test code here, this function is needed to manually copy it.
+  static std::unique_ptr<EntityData> CopyEntityData(const EntityData& old_data);
+
   const Store& db() { return *db_; }
 
  protected:
-  // Contains all of the data and metadata state.
-  std::unique_ptr<Store> db_;
-
- private:
   // Applies |change_list| to the metadata store.
   void ApplyMetadataChangeList(std::unique_ptr<MetadataChangeList> change_list);
 
-  // The conflict resolution to use for calls to ResolveConflict.
-  std::unique_ptr<ConflictResolution> conflict_resolution_;
+  // Contains all of the data and metadata state.
+  std::unique_ptr<Store> db_;
 
   // Whether an error should be produced on the next bridge call.
   bool error_next_ = false;
+
+ private:
+  // The conflict resolution to use for calls to ResolveConflict.
+  std::unique_ptr<ConflictResolution> conflict_resolution_;
 };
 
 }  // namespace syncer