Implement diff transformation for properties

Test: N/A
Change-Id: Ib231e617db3d87fe1abe20e95137d9af17572d19

tools/winscope/src/utils/diff.js

@@ -0,0 +1,10 @@
+const DiffType = Object.freeze({
+    NONE: 'none',
+    ADDED: 'added',
+    DELETED: 'deleted',
+    ADDED_MOVE: 'addedMove',
+    DELETED_MOVE: 'deletedMove',
+    MODIFIED: 'modified',
+});
+
+export { DiffType };